-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1
iQEcBAABAgAGBQJUX/DqAAoJEHm+PkMAQRiGLtQH/iAt3fRHlYDXjaJian/KG1Cb
wVP0I+HWZmvVmmd0PzyaxCZLgRNwdmmYHEH4QLy2JwZ3jZfFHlxhy+hDWCgz+67t
bIzkLs0Pf1T4kJ2+r8qW2kBEz9PWJHGTQw7NTqZ++Ts3rPptBA6Fg4mEJ6fQigXy
qRIY68DpipUkXV9BWBWijnTmrvP5tt7JtPzBr4DC8frMjvWct8+XwYhc2k2tEv2j
LwLYb1OW6PUpPv2BQBfWjqqH77vYNQVhJwuwGcDe2YZdI0UFkDheL24+RbbPcZ4f
OnrLjJSSgzv6lBWkAaXZK7/WJ/JZbXxEqHzWZQ3xXoQov97bm7lEYJqqi5gDasQ=
=6Qpa
-----END PGP SIGNATURE-----
Merge tag 'v3.18-rc4' into drm-next
backmerge to get vmwgfx locking changes into next as the
conflict with per-plane locking.
These two didn't get documented properly, do so.
Pointed out by Daniel.
v1.1: add missing boilerplate (Daniel)
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
So here's my atomic series, finally all debugged&reviewed. Sean Paul has
done a full detailed pass over it all, and a lot of other people have
commented and provided feedback on some parts. Rob Clark also converted
msm over the w/e and seems happy. The only small thing is that Rob wants
to export the wait_for_vblank, which imo makes sense. Since there's other
stuff still to do I think we should apply Rob's patch (once it has grown
appropriate kerneldoc) later on top of this.
This is just the core<->driver interface plus a big pile of helpers. Short
recap of the main ideas:
- There are essentially three helper libraries in this patch set:
* Transitional helpers to use the new plane callbacks for legacy plane
updates and in the crtc helper's ->mode_set callback. These helpers are
only temporarily used to convert drivers to atomic, but they allow a
nice separation between changing the driver backend and switching to
the atomic commit logic.
* Legacy helpers to implement all the legacy driver entry points
(page_flip, set_config, plane vfuncs) on top of the new atomic driver
interface. These are completely driver agnostic. The reason for having
the legacy support as helpers is that drivers can switch step-by-step.
And they could e.g. even keep the legacy page_flip code around for some
old platforms where converting to full-blown atomic isn't worth it.
* Atomic helpers which implement the various new ->atomic_* driver
interfaces in terms of the revised crtc helper and new plane helper
hooks.
- The revised crtc helper implemenation essentially implements all the
lessons learned in the i915 modeset rework (when using the atomic helpers
only):
* Enable/disable sequence for a given config are always the same and
callbacks are always called in the same order. This contrast starkly
with the crtc helpers, where the sequence of operations is heavily
dependent on the previous config.
One corollary of this is that if the configuration of a crtc only
partially changes (e.g. a connector moves in a cloned config) the
helper code will still disable/enable the full display pipeline. This
is the only way to ensure that the enable/disable sequence is always
the same.
* It won't call disable or enable hooks more than once any more because
it lost track of state, thanks to the atomic state tracking. And if
drivers implement the ->reset hook properly (by either resetting the hw
or reading out the hw state into the atomic structures) this even
extends to the hardware state. So no more disable-me-harder kind of
nonsense.
* The only thing missing is the hw state readout/cross-check support, but
if drivers have hw state readout support in their ->reset handlers it's
simple to extend that to cross-check the hw state.
* The crtc->mode_set callback is gone and its replacement only sets crtc
timings and no longer updates the primary plane state. This way we can
finally implement primary planes properly.
- The new plane helpers should be suitable enough for pretty much
everything, and a perfect fit for hardware with GO bits. Even if they
don't fit the atomic helper library is rather flexible and exports all
the functions for the individual steps to drivers. So drivers can pick
what matches and implement their own magic for everything else.
- A big difference compared to all previous atomic series is that this one
doesn't implement async commit in a generic way. Imo driver requirements
for that are too diverse to create anything reasonable sane which would
actually work on a reasonable amount of different drivers. Also, we've
never had a helper library for page_flips even, so it's really hard to
know what might work and what's stupid without a bit of experience in the form
of a few driver implementations.
I think with the current flexibility for drivers to pick individual
stages and existing helpers like drm_flip_queue it's rather easy though
to implement proper async commit.
- There's a few other differences of minor importance to earlier atomic
series:
* Common/generic properties are parsed in the callers/core and not in
drivers, and passed to drivers by directly setting the right members in
atomic state structures. That greatly simplifies all the transitional
and legacy helpers an removes a lot of boilerplate code.
* There's no crazy trylock mode used for the async commit since these
helpers don't do async commit. A simple ordered flip queue of atomic
state updates should be sufficient for preventing concurrent hw access
anyway, as long as synchronous updates stall correctly with e.g.
flush_work_queue or similar function. Abusing locks to enforce ordering
isn't a good idea imo anyway.
* These helpers reuse the existing ->mode_fixup hooks in the atomic_check
callback. Which means that drivers need to adapat and move a lot less code
into their atomic_check callbacks.
Now this isn't everything needed in the drm core and helpers for full
atomic support. But it's enough to start with converting drivers, and
except for actually testing multiplane and multicrtc updates also enough to
implement full atomic updates. Still missing are:
- Per-plane locking. Since these helpers here encapsulate the locking
completely this should be fairly easy to implement.
- fbdev support for atomic_check/commit, so that multi-pipe finally works
sanely in fbcon.
- Adding and decoding shared/core properties. That just needs to be rebased
from Rob's latest patch series, with minor adjustments so that the
decoding happens in the core instead of in drivers.
- Actually adding the atomic ioctl. Again just rebasing Rob's latest patch
should be all that's needed.
- Resolving how to deal with DPMS in atomic. Atomic is a good excuse to fix up
the crazy semantics dpms currently has. I'm floating an RFC about this topic
already.
- Finally I couldn't test connector/encoder stealing properly since my test
vehicle here doesn't allow a connector on different crtcs. So drivers
which support this might see some surprises in that area. There is no semantic
change though in how encoder stealing and assignment works (or at least no
intended one), so I think the risk is minimal.
As just mentioned I've done a fake conversion of an existing driver using
crtc helpers to debug the helper code and validate the smooth transition
approach. And that smooth transition was the really big motivation for
this. It seems to actually work and consists of 3 phases:
Phase 1: Rework driver backend for crtc/plane helpers
The requirement here is that universal plane support is already implement. If
universal plane support isn't implement yet it might be better though to just do
it as part of this phase, directly using the new plane helpers. There are two
big things to do:
- Split up the existing ->update/disable_plane hooks into check/commit
hooks and extract the crtc-wide prep/flush parts (like setting/clearing
GO bits).
- The other big change is to split the crtc->mode_set hook into the plane
update (done using the plane helpers) and the crtc setup in a new
->mode_set_nofb hook.
When phase 1 is complete the driver implements all the new callbacks which
push the software state into hardware, but still using all the legacy entry
points and crtc helpers. The transitional helpers serve as impendance
mismatch here.
Phase 2: Rework state handling
This consists of rolling out the state handling helpers for planes, crtcs
and connectors and reviewing all ->mode_fixup and similar hooks to make
sure they don't depend upon implicit global state which might change in the
atomic world. Any such code must be moved into ->atomic_check functions which
just rely on the free-standing atomic state update structures.
This phase also adds a few small pieces of fixup code to make sure the
atomic state doesn't get out of sync in the legacy driver callbacks.
Phase 3: Roll out atomic support
Now it's just about replacing vfuncs with the ones provided by the helper
and filling out the small missing pieces (like atomic_check logic or async
commit support needed for page_flips). Due to the prep work in phase 1 no
changes to the driver backend functions should be required, and because of
the prep work in phase 2 atomic implementations can be rolled out
step-by-step. So if async commit ins't implemented yet page_flip can be
implemented with the legacy functions without wreaking havoc in the other
operations.
* tag 'topic/atomic-helpers-2014-11-09' of git://anongit.freedesktop.org/drm-intel:
drm/atomic: Refcounting for plane_state->fb
drm: Docbook integration and over sections for all the new helpers
drm/atomic-helpers: functions for state duplicate/destroy/reset
drm/atomic-helper: implement ->page_flip
drm/atomic-helpers: document how to implement async commit
drm/atomic: Integrate fence support
drm/atomic-helper: implementatations for legacy interfaces
drm: Atomic crtc/connector updates using crtc/plane helper interfaces
drm/crtc-helper: Transitional functions using atomic plane helpers
drm/plane-helper: transitional atomic plane helpers
drm: Add atomic/plane helpers
drm: Global atomic state handling
drm: Add atomic driver interface definitions for objects
drm/modeset_lock: document trylock_only in kerneldoc
drm: fixup kerneldoc in drm_crtc.h
drm: Pull drm_crtc.h into the kerneldoc template
drm: Move drm_crtc_init from drm_crtc.h to drm_plane_helper.h
Just various stuff all over from a bunch of people. Shortlog gives a beter
overview, it's really all misc drm patches.
* tag 'topic/core-stuff-2014-11-05' of git://anongit.freedesktop.org/drm-intel:
drm/edid: add #defines and helpers for ELD
drm/dp: Add counters in the drm_dp_aux struct for I2C NACKs and DEFERs
drm: Remove compiler BUG_ON() test
drm: Fix DRM_FORCE_ON_DIGITAL use
drm/gma500: Don't destroy DRM properties in the driver
drm/i915: Don't destroy DRM properties in the driver
drm: Add a note to drm_property_create() about property lifetime
gpu: drm: Fix warning caused by a parameter description in drm_crtc.c
drm/dp-helper: Move the legacy helpers to gma500
drm/crtc: Remove duplicated ioctl code
drm/crtc: Fix two typos
gpu:drm: Fix typo in Documentation/DocBook/drm.xml
gpu: drm: drm_dp_mst_topology.c: Fix improper use of strncat
drm: drm_err: Remove unnecessary __func__ argument
drm: Implement O_NONBLOCK support on /dev/dri/cardN
This stuff is ancient, we have docs now in the kernel,
lets just drop it.
Pointed out by Glenn
Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
So my original plan was that the drm core refcounts framebuffers like
with the legacy ioctls. But that doesn't work for a bunch of reasons:
- State objects might live longer than until the next fb change
happens for a plane. For example delayed cleanup work only happens
_after_ the pageflip ioctl has completed. So this definitely doesn't
work without the plane state holding its own references.
- The other issue is transition from legacy to atomic implementations,
where the driver works under a mix of both worlds. Which means
legacy paths might not properly update the ->fb pointer under
plane->state->fb. Which is a bit a problem when then someone comes
around and _does_ try to clean it up when it's long gone.
The second issue is just a bit a transition bug, since drivers should
update plane->state->fb in all the paths that aren't converted yet.
But a bit more robustness for the transition can't hurt - we pull
similar tricks with cleaning up the old fb in the transitional helpers
already.
The pattern for drivers that transition is
if (plane->state)
drm_atomic_set_fb_for_plane(plane->state, plane->fb);
inserted after the fb update has logically completed at the end of
->set_config (or ->set_base/mode_set if using the crtc helpers),
->page_flip, ->update_plane or any other entry point which updates
plane->fb.
v2: Update kerneldoc - copypasta fail.
v3: Fix spelling in the commit message (Sean).
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
In all cases the text requires that new drivers are converted to the
atomic interfaces.
v2: Add overview for state handling.
v3: Review from Sean: Some spelling fixes and drop the misguided
hunk to remove rgba8888 from the plane helpers compat list.
Cc: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The atomic users and helpers assume that there is always a obj->state
structure around. Which means drivers need to somehow create that at
driver load time. Also it should obviously reset hardware state, so
needs to be reset upon resume.
Finally the destroy/duplicate_state functions are an awful lot of
boilerplate if the driver doesn't need anything beyond the default
state objects.
So add helper functions for all of this.
v2: Somehow the plane/connector versions got lost in the first
version.
v3: Add kerneldoc.
v4: Make duplicate_state functions a bit more robust, which is useful
for debugging state tracking issues when transitioning to atomic.
v5: Clear temporary variables in the crtc state when duplicating it,
like ->mode_changed or ->planes_changed. If we don't do this stale
values for these might pollute the next atomic modeset.
v6: Also clear crtc_state->event in case the driver didn't (yet) clear
this out.
v7: Split out wrong squashed commit. Also improve the kerneldoc to
mention that obj->state can be NULL and when. Both suggested by
Daniel Thompson.
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Currently there is no way to implement async flips using atomic, that
essentially requires us to be able to cancel pending requests
mid-flight.
To be able to do that (and I guess we want this since vblank synced
updates which opportunistically cancel still pending updates seem to be
wanted) we'd need to add a mandatory cancellation mode. Depending upon
the exact semantics we decide upon that could mean that userspace will
not get completion events, or will get them all stacked up.
So reject async updates for now. Also async updates usually means not
vblank synced at all, and I guess for drivers which want to support
this they should simply add a special pageflip handler (since usually
you need a special flip cmd to achieve this). That kind of async flip
is pretty much exclusively just used for games and benchmarks where
dropping just one frame means you'll get a headshot or something bad
like that ... And so slight amounts of tearing is acceptable.
v2: Fixup kerneldoc, reported by Paulo.
v3: Use the set_crtc_for_plane function to assign the crtc, since
otherwise the book-keeping is off.
v4: Update crtc->primary->fb since ->page_flip is the only driver
callback where the core won't do this itself. We might want to fix
this inconsistency eventually.
v5: Use set_crtc_for_connector as suggested by Sean.
v6: Daniel Thompson noticed that my error handling is inconsistent
and that in a few cases I didn't handle fatal errors (i.e. not
-EDEADLK). Fix this by consolidate the ww mutex backoff handling
into one check in the fail: block and flatten the error control
flow everywhere else.
v7: Fix spelling mistake in the commit message (Sean).
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Paulo Zanoni <przanoni@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
No helper function to do it all yet provided since no driver has
support for driver core fences yet. Which we'd need to make the
implementation really generic.
v2: Clarify async howto a bit per the discussion With Rob Clark.
Cc: Rob Clark <robdclark@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This patch is for enabling async commits. It replaces an earlier
approach which added an async boolean paramter to the ->prepare_fb
callbacks. The idea is that prepare_fb picks up the right fence to
synchronize against, which is then used by the synchronous commit
helper. For async commits drivers can either register a callback to
the fence or simply do the synchronous wait in their async work queue.
v2: Remove unused variable.
v3: Only wait for fences after the point of no return in the part
of the commit function which can be run asynchronously. This is after
the atomic state has been swapped in, hence now check
plane->state->fence.
Also add a WARN_ON to make sure we don't try to wait on a fence when
there's no fb, just as a sanity check.
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Well, except page_flip since that requires async commit, which isn't
there yet.
For the functions which changes planes there's a bit of trickery
involved to keep the fb refcounting working. But otherwise fairly
straight-forward atomic updates.
The property setting functions are still a bit incomplete. Once we
have generic properties (e.g. rotation, but also all the properties
needed by the atomic ioctl) we need to filter those out and parse them
in the helper. Preferrably with the same function as used by the real
atomic ioctl implementation.
v2: Fixup kerneldoc, reported by Paulo.
v3: Add missing EXPORT_SYMBOL.
v4: We need to look at the crtc of the modeset, not some random
leftover one from a previous loop when udpating the connector->crtc
routing. Also push some local variables into inner loops to avoid
these kinds of bugs.
v5: Adjust semantics - drivers now own the atomic state upon
successfully synchronous commit.
v6: Use the set_crtc_for_plane function to assign the crtc, since
otherwise the book-keeping is off.
v7:
- Improve comments.
- Filter out the crtc of the ->set_config call when recomputing
crtc_state->enabled: We should compute the same state, but not doing
so will give us a good chance to catch bugs and inconsistencies -
the atomic helper's atomic_check function re-validates this again.
- Fix the set_config implementation logic when disabling the crtc: We
still need to update the output routing to disable all the
connectors properly in the state. Caught by the atomic_check
functions, so at least that part worked ;-) Also add some WARN_ONs
to ensure ->set_config preconditions all apply.
v8: Fixup an embarrassing h/vdisplay mixup.
v9: Shuffled bad squash to the right patch, spotted by Daniel
v10: Use set_crtc_for_connector as suggested by Sean.
v11: Daniel Thompson noticed that my error handling is inconsistent
and that in a few cases I didn't handle fatal errors (i.e. not
-EDEADLK). Fix this by consolidate the ww mutex backoff handling
into one check in the fail: block and flatten the error control
flow everywhere else.
v12: Review and discussion with Sean:
- One spelling fix.
- Correctly skip the crtc from the set_config set when recomputing
->enable state. That should allow us to catch any bugs in higher
levels in computing that state (which is supplied to the
->set_config implementation). I've screwed this up and Sean spotted
that the current code is pointless.
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Paulo Zanoni <przanoni@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
So this is finally the integration of the crtc and plane helper
interfaces into the atomic helper functions.
In the check function we now have a few steps:
- First we update the output routing and figure out which crtcs need a
full mode set. Suitable encoders are selected using ->best_encoder,
with the same semantics as the crtc helpers of implicitly disabling
all connectors currently using the encoder.
- Then we pull all other connectors into the state update which feed
from a crtc which changes. This must be done do catch mode changes
and similar updates - atomic updates are differences on top of the
current state.
- Then we call all the various ->mode_fixup to compute the adjusted
mode. Note that here we have a slight semantic difference compared
to the crtc helpers: We have not yet updated the encoder->crtc link
when calling the encoder's ->mode_fixup function. But that's a
requirement when converting to atomic since we want to prepare the
entire state completely contained with the over drm_atomic_state
structure. So this must be carefully checked when converting drivers
over to atomic helpers.
- Finally we do call the atomic_check functions on planes and crtcs.
The commit function is also quite a beast:
- The only step that can fail is done first, namely pinning the
framebuffers. After that we cross the point of no return, an async
commit would push all that into the worker thread.
- The disabling of encoders and connectors is a bit tricky, since
depending upon the final state we need to select different crtc
helper functions.
- Software tracking is a bit clarified compared to the crtc helpers:
We commit the software state before starting to touch the hardware,
like crtc helpers. But since we just swap them we still have the old
state (i.e. the current hw state) around, which is really handy to
write simple disable functions. So no more
drm_crtc_helper_disable_all_unused_functions kind of fun because
we're leaving unused crtcs/encoders behind. Everything gets shut
down in-order now, which is one of the key differences of the i915
helpers compared to crtc helpers and a really nice additional
guarantee.
- Like with the plane helpers the atomic commit function waits for one
vblank to pass before calling the framebuffer cleanup function.
Compared to Rob's helper approach there's a bunch of upsides:
- All the interfaces which can fail are called in the ->check hook
(i.e. ->best_match and the various ->mode_fixup hooks). This means
that drivers can just reuse those functions and don't need to move
everything into ->atomic_check callbacks. If drivers have no need
for additional constraint checking beyong their existing crtc
helper callbacks they don't need to do anything.
- The actual commit operation is properly stage: First we prepare
framebuffers, which can potentially still fail (due to memory
exhausting). This is important for the async case, where this must
be done synchronously to correctly return errors.
- The output configuration changes (done with crtc helper functions)
and the plane update (using atomic plane helpers) are correctly
interleaved: First we shut down any crtcs that need changing, then
we update planes and finally we enable everything again. Hardware
without GO bits must be more careful with ordering, which this
sequence enables.
- Also for hardware with shared output resources (like display PLLs)
we first must shut down the old configuration before we can enable
the new one. Otherwise we can hit an impossible intermediate state
where there's not enough PLLs (which is the point behind atomic
updates).
v2:
- Ensure that users of ->check update crtc_state->enable correctly.
- Update the legacy state in crtc/plane structures. Eventually we want
to remove that, but for now the drm core still expects this (especially
the plane->fb pointer).
v3: A few changes for better async handling:
- Reorder the software side state commit so that it happens all before
we touch the hardware. This way async support becomes very easy
since we can punt all the actual hw touching to a worker thread. And
as long as we synchronize with that thread (flushing or cancelling,
depending upon what the driver can handle) before we commit the next
software state there's no need for any locking in the worker thread
at all. Which greatly simplifies things.
And as long as we synchronize with all relevant threads we can have
a lot of them (e.g. per-crtc for per-crtc updates) running in
parallel.
- Expose pre/post plane commit steps separately. We need to expose the
actual hw commit step anyway for drivers to be able to implement
asynchronous commit workers. But if we expose pre/post and plane
commit steps individually we allow drivers to selectively use atomic
helpers.
- I've forgotten to call encoder/bridge ->mode_set functions, fix
this.
v4: Add debug output and fix a mixup between current and new state
that resulted in crtcs not getting updated correctly. And in an
Oops ...
v5:
- Be kind to driver writers in the vblank wait functions.. if thing
aren't working yet, and vblank irq will never come, then let's not
block forever.. especially under console-lock.
- Correctly clear connector_state->best_encoder when disabling.
Spotted while trying to understand a report from Rob Clark.
- Only steal encoder if it actually changed, otherwise hilarity ensues
if we steal from the current connector and so set the ->crtc pointer
unexpectedly to NULL. Reported by Rob Clark.
- Bail out in disable_outputs if an output currently doesn't have a
best_encoder - this means it's already disabled.
v6: Fixupe kerneldoc as reported by Paulo. And also fix up kerneldoc
in drm_crtc.h.
v7: Take ownership of the atomic state and clean it up with
drm_atomic_state_free().
v8 Various improvements all over:
- Polish code comments and kerneldoc.
- Improve debug output to make sure all failure cases are logged.
- Treat enabled crtc with no connectors as invalid input from userspace.
- Don't ignore the return value from mode_fixup().
v9:
- Improve debug output for crtc_state->mode_changed.
v10:
- Fixup the vblank waiting code to properly balance the vblank_get/put
calls.
- Better comments when checking/computing crtc->mode_changed
v11: Fixup the encoder stealing logic: We can't look at encoder->crtc
since that's not in the atomic state structures and might be updated
asynchronously in and async commit. Instead we need to inspect all the
connector states and check whether the encoder is currently in used
and if so, on which crtc.
v12: Review from Sean:
- A few spelling fixes.
- Flatten control flow indent by converting if blocks to early
continue/return in 2 places.
- Capture connectors_for_crtc return value in int num_connectors
instead of bool has_connectors and do an explicit int->bool
conversion with !!. I think the helper is more useful for drivers if
it returns the number of connectors (e.g. to detect cloning
configurations), so decided to keep that return value.
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Paulo Zanoni <przanoni@gmail.com>
Cc: Rob Clark <robdclark@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
These two functions allow drivers to reuse their atomic plane helpers
functions for the primary plane to implement the interfaces required
by the crtc helpers for the legacy ->set_config callback.
This is purely transitional and won't be used once the driver is fully
converted. But it allows partial conversions to the atomic plane
helpers which are functional.
v2:
- Use ->atomic_duplicate_state if available.
- Don't forget to run crtc_funcs->atomic_check.
v3: Shift source coordinates correctly for 16.16 fixed point.
v4: Don't forget to call ->atomic_destroy_state if available.
v5: Fixup kerneldoc.
v6: Reuse the plane_commit function from the transitional plane
helpers to avoid too much duplication.
v7:
- Remove some stale comment.
- Correctly handle the lack of plane->state object, necessary for
transitional use.
v8: Fixup an embarrassing h/vdisplay mixup.
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Converting a driver to the atomic interface can be a daunting
undertaking. One of the prerequisites is to have full universal planes
support.
To make that transition a bit easier this patch provides plane helpers
which use the new atomic helper callbacks just only for the plane
changes. This way the plane update functionality can be tested without
being forced to convert everything at once.
Of course a real atomic update capable driver will implement the
all plane properties through the atomic interface, so these helpers
are mostly transitional. But they can be used to enable proper
universal plane support, especially once the crtc helpers have also
been adapted.
v2: Use ->atomic_duplicate_state if available.
v3: Don't forget to call ->atomic_destroy_state if available.
v4: Fixup kerneldoc, reported by Paulo.
v5: Extract a common plane_commit helper and fix some bugs in the
plane_state setup of the plane_disable implementation.
v6: Fix issues with the cleanup of the old fb. Since transitional
helpers can be mixed we need to assume that the old fb has been set up
by a legacy path (e.g. set_config or page_flip when the primary plane
is converted to use these functions already). Hence pass an additional
old_fb parameter to plane_commit to do that cleanup work correctly.
v7:
- Fix spurious WARNING (crtc helpers really love to disable stuff
harder) and fix array index bonghits.
- Correctly handle the lack of plane->state object, necessary for
transitional use.
- Don't indicate failure if drm_vblank_get doesn't work - that's
expected when the pipe is in dpms off mode.
v8: Review from Sean:
- s/fail/out/ to make the meaning of a label more clear.
- spelling fix in the commit message.
Cc: Paulo Zanoni <przanoni@gmail.com>
Cc: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This is the first cut of atomic helper code. As-is it's only useful to
implement a pure atomic interface for plane updates.
Later patches will integrate this with the crtc helpers so that full
atomic updates are possible. We also need a pile of helpers to aid
drivers in transitioning from the legacy world to the shiny new atomic
age. Finally we need helpers to implement legacy ioctls on top of the
atomic interface.
The design of the overall helpers<->driver interaction is fairly
simple, but has an unfortunate large interface:
- We have ->atomic_check callbacks for crtcs and planes. The idea is
that connectors don't need any checking, and if they do they can
adjust the relevant crtc driver-private state. So no connector hooks
should be needed. Also the crtc helpers integration will do the
->best_encoder checks, so no need for that.
- Framebuffer pinning needs to be done before we can commit to the hw
state. This is especially important for async updates where we must
pin all buffers before returning to userspace, so that really only
hw failures can happen in the asynchronous worker.
Hence we add ->prepare_fb and ->cleanup_fb hooks for this resources
management.
- The actual atomic plane commit can't fail (except hw woes), so has
void return type. It has three stages:
1. Prepare all affected crtcs with crtc->atomic_begin. Drivers can
use this to unset the GO bit or similar latches to prevent plane
updates.
2. Update plane state by looping over all changed planes and calling
plane->atomic_update. Presuming the hardware is sane and has GO
bits drivers can simply bash the state into the hardware in this
function. Other drivers might use this to precompute hw state for
the final step.
3. Finally latch the update for the next vblank with
crtc->atomic_flush. Note that this function doesn't need to wait
for the vblank to happen even for the synchronous case.
v2: Clear drm_<obj>_state->state to NULL when swapping in state.
v3: Add TODO that we don't short-circuit plane updates for now. Likely
no one will care.
v4: Squash in a bit of polish that somehow landed in the wrong (later)
patche.
v5: Integrate atomic functions into the drm docbook and fixup the
kerneldoc.
v6: Fixup fixup patch squashing fumble.
v7: Don't touch the legacy plane state plane->fb and plane->crtc. This
is only used by the legacy ioctl code in the drm core, and that code
already takes care of updating the pointers in all relevant cases.
This is in stark contrast to connector->encoder->crtc links on the
modeset side, which we still need to set since the core doesn't touch
them.
Also some more kerneldoc polish.
v8: Drop outdated comment.
v9: Handle the state->state pointer correctly: Only clearing the
->state pointer when assigning the state to the kms object isn't good
enough. We also need to re-link the swapped out state into the
drm_atomic_state structure.
v10: Shuffle the misplaced docbook template hunk around that Sean spotted.
Cc: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Some differences compared to Rob's patches again:
- Dropped the committed and checked booleans. Checking will be
internally enforced by always calling ->atomic_check before
->atomic_commit. And async handling needs to be solved differently
because the current scheme completely side-steps ww mutex deadlock
avoidance (and so either reinvents a new deadlock avoidance wheel or
like the current code just deadlocks).
- State for connectors needed to be added, since now they have a
full-blown drm_connector_state (so that drivers have something to
attach their own stuff to).
- Refcounting is gone. I plane to solve async updates differently,
since the lock-passing scheme doesn't cut it (since it abuses ww
mutexes). Essentially what we need for async is a simple ownership
transfer from the caller to the driver. That doesn't need full-blown
refcounting.
- The acquire ctx is a pointer. Real atomic callers should have that
on their stack, legacy entry points need to put the right one
(obtained by drm_modeset_legacy_acuire_ctx) in there.
- I've dropped all hooks except check/commit. All the begin/end
handling is done by core functions and is the same.
- commit/check are just thin wrappers that ensure that ->check is
always called.
- To help out with locking in the legacy implementations I've added a
helper to just grab all locks in the backoff case.
v2: Add notices that check/commit can fail with EDEADLK.
v3:
- More consistent naming for state_alloc.
- Add state_clear which is needed for backoff and retry.
v4: Planes/connectors can switch between crtcs, and we need to be
careful that we grab the state (and locks) for both the old and new
crtc. Improve the interface functions to ensure this.
v5: Add functions to grab affected connectors for a crtc and to recompute
the crtc->enable state. This is useful for both helper and atomic ioctl
code when e.g. removing a connector.
v6: Squash in fixup from Fengguang to use ERR_CAST.
v7: Add debug output.
v8: Make checkpatch happy about kcalloc argument ordering.
v9: Improve kerneldoc in drm_crtc.h
v10:
- Fix another kcalloc argument misorder I've missed.
- More polish for kerneldoc.
v11: Clarify the ownership rules for the state object. The new rule is
that a successful drm_atomic_commit (whether synchronous or asnyc)
always inherits the state and is responsible for the clean-up. That
way async and sync ->commit functions are more similar.
v12: A few bugfixes:
- Assign state->state pointers correctly when grabbing state objects -
we need to link them up with the global state.
- Handle a NULL crtc in set_crtc_for_plane to simplify code flow a bit
for the callers of this function.
v13: Review from Sean:
- kerneldoc spelling fixes
- Don't overallocate states->planes.
- Handle NULL crtc in set_crtc_for_connector.
v14: Sprinkle __must_check over all functions which do wait/wound
locking to make sure callers don't forget this. Since I have ;-)
v15: Be more explicit in the kerneldoc when functions can return
-EDEADLK what to do. And that every other -errno is fatal.
v16: Indent with tabs instead of space, spotted by Ander.
v17: Review from Thierry, small kerneldoc and other naming polish.
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
These counters are used for Displayort compliance testing to detect error
conditions when executing tests 4.2.2.4 and 4.2.2.5 in the Displayport Link
CTS specificaiton. They determine whether to use the preferred/requested
mode or the failsafe mode during these tests.
V2:
- Addressed previous review feedback
- Updated commit message
- Changed from uint8_t to uint32_t
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Todd Previte <tprevite@gmail.com>
[danvet: s/uint32_t/unsigned/ for clearer intent. Also drop the i915
from the subject, it's all core stuff.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Just a bit of OCD cleanup on headers - this function isn't the core
interface any more but just a helper for drivers who haven't yet
transitioned to universal planes. Put the declaration at the right
spot and sprinkle necessary #includes over all drivers.
Maybe this helps to encourage driver maintainers to do the switch.
v2: Fix #include ordering for tegra, reported by 0-day builder.
v3: Include required headers, reported by Thierry.
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Thierry Reding <treding@nvidia.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
modeset->num_connectors must be 0 to reach the BUG_ON() which tests
for non-zero modeset->num_connectors; remove BUG_ON().
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
A connector may be forced on from the command line via video=
command line setting. The digital output of dual-mode connectors
can also be specifically selected and forced on; eg., 'video=DVI-I-2:D'.
However, in this case, the connector->status will be mistakenly set to
connector_status_disconnected, and the connector will not be mode set.
Fix the connector->status when connector->force is DRM_FORCE_ON_DIGITAL.
Note that this seems to have been broken ever since the introduction
of the connector forcing support in
commit d50ba256b5
Author: Dave Airlie <airlied@linux.ie>
Date: Wed Sep 23 14:44:08 2009 +1000
drm/kms: start adding command line interface using fb.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
[danvet: Add note about that this never worked.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
- suspend/resume/freeze/thaw unification from Imre
- wa list improvements from Mika&Arun
- display pll precomputation from Ander Conselvan, this removed the last
->mode_set callbacks, a big step towards implementing atomic modesets
- more kerneldoc for the interrupt code
- 180 rotation for cursors (Ville&Sonika)
- ULT/ULX feature check macros cleaned up thanks to Damien
- piles and piles of fixes all over, bug team seems to work!
* tag 'drm-intel-next-2014-10-24' of git://anongit.freedesktop.org/drm-intel: (61 commits)
drm/i915: Update DRIVER_DATE to 20141024
drm/i915: add comments on what stage a given PM handler is called
drm/i915: unify switcheroo and legacy suspend/resume handlers
drm/i915: add poweroff_late handler
drm/i915: sanitize suspend/resume helper function names
drm/i915: unify S3 and S4 suspend/resume handlers
drm/i915: disable/re-enable PCI device around S4 freeze/thaw
drm/i915: enable output polling during S4 thaw
drm/i915: check for GT faults in all resume handlers and driver load time
drm/i915: remove unused restore_gtt_mappings optimization during suspend
drm/i915: fix S4 suspend while switcheroo state is off
drm/i915: vlv: fix switcheroo/legacy suspend/resume
drm/i915: propagate error from legacy resume handler
drm/i915: unify legacy S3 suspend and S4 freeze handlers
drm/i915: factor out i915_drm_suspend_late
drm/i915: Emit even number of dwords when emitting LRIs
drm/i915: Add rotation support for cursor plane (v5)
drm/i915: Correctly reject invalid flags for wait_ioctl
drm/i915: use macros to assign mmio access functions
drm/i915: only run hsw_power_well_post_enable when really needed
...
During system suspend after connector switch off its dpms field
is set to connector previous dpms state. To properly resume dpms field
should be set to its actual state (off) before resuming to previous dpms state.
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Before DPMS off driver disables vblank.
It should be balanced by vblank enable after DPMS on.
The patch fixes issue with page_flip ioctl not being able
to acquire vblank counter introduced by patch:
drm: Always reject drm_vblank_get() after drm_vblank_off()
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
HPD events can be generated by components even if drm_dev is not fully
initialized, to skip such events kms poll initialization should
be performed at the end of load callback followed directly by forced
connection detection.
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
In case of error during plane initialization load callback
incorrectly return success, this patch fixes it.
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
All KMS objects are destroyed by drm_mode_config_cleanup in proper order
so component drivers should not care about it.
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Initialization of vblank with MAX_CRTC caused attempts
to disabling vblanks for non-existing crtcs in case
drm used fewer crtcs. The patch fixes it.
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
When drm properties are created, they are added to mode_config.property_list
which is then used in drm_mode_config_cleanup() to destroy every single
property created by the driver.
Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
When drm properties are created, they are added to mode_config.property_list,
which is then used in drm_mode_config_cleanup() to destroy every single
property created by the driver.
Cc: Chandra Konduru <chandra.konduru@intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
When screen objects are enabled, the bpp is assumed to be 32, otherwise
it is set to 16.
v2:
* Use u32 instead of u64 for assumed_bpp.
* Fixed mechanism to check for screen objects
* Limit the back buffer size to VRAM.
Signed-off-by: Sinclair Yeh <syeh@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Cc: <stable@vger.kernel.org>
The hash key computation in vmw_cmdbuf_res_remove incorrectly didn't take
the resource type into account, contrary to all the other related functions.
This becomes important when the cmdbuf resource manager handles more than
one resource type.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
After:
commit d059f652e7
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
AuthorDate: Fri Jul 25 18:07:40 2014 +0200
drm: Handle legacy per-crtc locking with full acquire ctx
drm_mode_cursor_common() was switched to use drm_modeset_(un)lock_crtc()
which uses full aquire ctx. So dropping/reaquiring the lock via
drm_modeset_(un)lock() directly isn't the right thing to do, as lockdep
kindly points out.
The 'FIXME's about sorting out whether vmwgfx *really* needs to lock-all
for cursor updates still apply.
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Tested-by: Thomas Hellstrom <thellstrom@vmware.com>
- dpm stability fixes for SI and KV
- remove an invalid pci id
- kmalloc_array fixes
- minor cleanups
* 'drm-fixes-3.18' of git://people.freedesktop.org/~agd5f/linux:
drm/radeon: remove some buggy dead code
drm/radeon: remove invalid pci id
drm/radeon: dpm fixes for asrock systems
radeon: clean up coding style differences in radeon_get_bios()
drm/radeon: Use drm_malloc_ab instead of kmalloc_array
drm/radeon/dpm: disable ulv support on SI
bunch of DP fixes, and some backlight fix.
* tag 'drm-intel-fixes-2014-10-30' of git://anongit.freedesktop.org/drm-intel:
drm/i915/dp: only use training pattern 3 on platforms that support it
drm/i915: Ignore VBT backlight check on Macbook 2, 1
drm/i915: Fix GMBUSFREQ on vlv/chv
drm/i915: Ignore long hpds on eDP ports
drm/i915: Do a dummy DPCD read before the actual read
Ivybridge + 30" monitor prints a drm error on every modeset, since IVB
doesn't support DP3 we should even bother trying to use it.
This regression has been introduced in
commit 06ea66b6bb
Author: Todd Previte <tprevite@gmail.com>
Date: Mon Jan 20 10:19:39 2014 -0700
drm/i915: Enable 5.4Ghz (HBR2) link rate for Displayport 1.2-capable
devices
Reported-by: Dave Airlie <airlied@redhat.com>
Reference: http://mid.gmane.org/1414566170-9868-1-git-send-email-airlied@gmail.com
Cc: Todd Previte <tprevite@gmail.com>
Cc: stable@vger.kernel.org (3.15+)
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
The calculation of "num_shader_engines" has a precedence bug because
the right shift happens before the mask, but this variable is never used
so we can just delete it.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
commit c675949ec5
Author: Jani Nikula <jani.nikula@intel.com>
Date: Wed Apr 9 11:31:37 2014 +0300
drm/i915: do not setup backlight if not available according to VBT
prevents backlight setup on Macbook 2,1. Apply quirk to ignore the VBT
check so backlight is set up properly.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=81438
Signed-off-by: Jens Stein Jørgensen <jens.s.stein@gmail.com>
Cc: stable@vger.kernel.org (3.15+)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Should avoid kmalloc failures due to large number of array entries.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=81991
Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Ok, new attempt, this time around with full ppgtt disabled again.
drm-intel-next-2014-10-03:
- first batch of skl stage 1 enabling
- fixes from Rodrigo to the PSR, fbc and sink crc code
- kerneldoc for the frontbuffer tracking code, runtime pm code and the basic
interrupt enable/disable functions
- smaller stuff all over
drm-intel-next-2014-09-19:
- bunch more i830M fixes from Ville
- full ppgtt now again enabled by default
- more ppgtt fixes from Michel Thierry and Chris Wilson
- plane config work from Gustavo Padovan
- spinlock clarifications
- piles of smaller improvements all over, as usual
* tag 'drm-intel-next-2014-10-03-no-ppgtt' of git://anongit.freedesktop.org/drm-intel: (114 commits)
Revert "drm/i915: Enable full PPGTT on gen7"
drm/i915: Update DRIVER_DATE to 20141003
drm/i915: Remove the duplicated logic between the two shrink phases
drm/i915: kerneldoc for interrupt enable/disable functions
drm/i915: Use dev_priv instead of dev in irq setup functions
drm/i915: s/pm._irqs_disabled/pm.irqs_enabled/
drm/i915: Clear TX FIFO reset master override bits on chv
drm/i915: Make sure hardware uses the correct swing margin/deemph bits on chv
drm/i915: make sink_crc return -EIO on aux read/write failure
drm/i915: Constify send buffer for intel_dp_aux_ch
drm/i915: De-magic the PSR AUX message
drm/i915: Reinstate error level message for non-simulated gpu hangs
drm/i915: Kerneldoc for intel_runtime_pm.c
drm/i915: Call runtime_pm_disable directly
drm/i915: Move intel_display_set_init_power to intel_runtime_pm.c
drm/i915: Bikeshed rpm functions name a bit.
drm/i915: Extract intel_runtime_pm.c
drm/i915: Remove intel_modeset_suspend_hw
drm/i915: spelling fixes for frontbuffer tracking kerneldoc
drm/i915: Tighting frontbuffer tracking around flips
...
Three changes for the Armada DRM driver:
1. Add back the flags which tell the DRM core that we can do vblank. This
was removed in error during the recent restructuring, and came to light
while trying textured Xv rendering.
2. Fixing a refcount leak with Xv overlay.
3. As per recent discussion, the drm_vblank_pre_modeset() calls can cause
deadlock with other changes to generic code. This change prevents those
deadlocks by switching to the drm_crtc_vblank_*() calls instead.
* 'drm-armada-fixes' of git://ftp.arm.linux.org.uk/~rmk/linux-arm:
drm/armada: convert to use vblank_on/off calls
drm/armada: fix page_flip refcounting leak
drm/armada: add IRQ support back
vlv_cdclk_freq is in kHz but we need MHz for the GMBUSFREQ divider.
This is a regression from:
commit f8bf63fdcb
Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
Date: Fri Jun 13 13:37:54 2014 +0300
drm/i915: Kill duplicated cdclk readout code from i2c
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Turning vdd on/off can generate a long hpd pulse on eDP ports. In order
to handle hpd we would need to turn on vdd to perform aux transfers.
This would lead to an endless cycle of
"vdd off -> long hpd -> vdd on -> detect -> vdd off -> ..."
So ignore long hpd pulses on eDP ports. eDP panels should be physically
tied to the machine anyway so they should not actually disappear and
thus don't need long hpd handling. Short hpds are still needed for link
re-train and whatnot so we can't just turn off the hpd interrupt
entirely for eDP ports. Perhaps we could turn it off whenever the panel
is disabled, but just ignoring the long hpd seems sufficient.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Todd Previte <tprevite@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Sometimes we seem to get utter garbage from DPCD reads. The resulting
buffer is filled with the same byte, and the operation completed without
errors. My HP ZR24w monitor seems particularly susceptible to this
problem once it's gone into a sleep mode.
The issue seems to happen only for the first AUX message that wakes the
sink up. But as the first AUX read we often do is the DPCD receiver
cap it does wreak a bit of havoc with subsequent link training etc. when
the receiver cap bw/lane/etc. information is garbage.
A sufficient workaround seems to be to perform a single byte dummy read
before reading the actual data. I suppose that just wakes up the sink
sufficiently and we can just throw away the returned data in case it's
crap. DP_DPCD_REV seems like a sufficiently safe location to read here.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Todd Previte <tprevite@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
