Insert a wait parameter in the code so we can possibly timeout on a
seqno wait if need be. The code should be functionally the same as
before because all the callers will continue to retry if an arbitrary
timeout elapses.
We'd like to have nanosecond granularity, but the only way to do this is
with hrtimer, and that doesn't fit well with the needs of this code.
v2: Fix rebase error (Chris)
Return proper time even in wedged + signal case (Chris + Ben)
Use timespec constructs (Ben)
Didn't take Daniel's advice regarding the Frankenstein-ness of the
function. I did try his advice, but in the end I liked the way the
original code looked, better.
v3: Make wakeups far less frequent for infinite waits (Chris)
v4: Remove dummy_wait variable (Daniel)
Use raw monotonic time instead of jiffies (made the code a bit cleaner) (Ben)
Added a couple of warnings (Ben)
v5: Remove warnings (Daniel)
Use more accurate time diff for default case (Daniel)
Bikeshed for setting the return timespec in timeout case (Daniel)
s/jiffies/time in one of the comments
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Unfortunately we can't abort a mode_set, but at least tell the user
that something might have gone wrong when setting the sdvo input or
output timing fails.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
- kill intel_sdvo->input_dtd, it's only used as a temporary variable,
we store the preferred input mode in the adjusted mode at mode_fixup
time.
- rename the function to make it clear what we want it to do (get the
preferred mode) and say in a comment what it unfortunately does as a
side-effect (set the new output timings).
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Similar to g4x_dp_detect() we should probe the PORT_HOTPLUG_STATUS as to
whether the connector is active prior to attempting to retrieve the EDID.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Note that gen3 is the only platform where we've got the bit
definitions right, hence the workaround of disabling sdvo hotplug
support on i945g/gm is not due to misdiagnosis of broken hotplug irq
handling ...
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: add some blurb about sdvo hotplug fail on i945g/gm I've
wondered about while reviewing.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The status bits corresponding to the interrupt enable bits are the
"live" hotplug status bits, and reflect the current status of the port
(high for a detected connection, low for a disconnect). The actual bits
corresponding to the interrupt source are elsewhere. The actual event is
then determined by a combination of the interrupt flag and the current
live status (if the interrupt is active, but the current status is not,
then we have detected a disconnect.)
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Also as we set the HOTPLUG_EN to 0 during pre-install, we can simply set
it during post-install, and nor do we wish to enable unwanted hotplug
events.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Daniel wrote:
The last pull I'd like to squeeze into 3.5, safe for the hsw stuff mostly
bugfixes:
- last few patches for basic hsw enabling (Eugeni, infoframe support by
Paulo)
- Fix up infoframe support, we've hopefully squashed all the cargo-culting
in there (Paulo). Among all the issues, this finally fixes some of the
infoframe regressions seen on g4x and snb systems.
- Fixup sdvo infoframe support, this fixes a regression from 2.6.37.
- Correctly enable semaphores on snb, we've enabled it already for 3.5,
but the dmar check was slightly wrong.
- gen6 irq fixlets from Chris.
- disable gmbus on i830, the hw seems to be simply broken.
- fix up the pch pll fallout (Chris & me).
- for_each_ring macro from Chris - I've figured I'll merge this now to
avoid backport pain.
- complain when the rps state isn't what we expect (Chris). Note that this
is shockingly easy to hit and hence pretty much will cause a regression
report. But it only tells us that the gpu turbo state got out of whack,
a problem we know off since a long time (it cause the gpu to get stuck a
a fixed frequency, usually the lowest one). Chris is working on a fix,
but we haven't yet found a magic formula that works perfectly (only
patches that massively reduce the frequency of this happening).
- MAINTAINERS patch, I'm now officially the guy to beat up."
* tag 'drm-intel-next-2012-05-20' of git://people.freedesktop.org/~danvet/drm-intel: (57 commits)
drm/i915: IBX has a fixed pch pll to pch pipe mapping
drm/i915: implement hsw_write_infoframe
drm/i915: small hdmi coding style cleanups
drm/i915: fixup infoframe support for sdvo
drm/i915: Enable the PCH PLL for all generations after link training
drm/i915: Convert BUG_ON(!pll->active) and friends to a WARN
drm/i915: don't clobber the pipe param in sanitize_modesetting
drm/i915: disable gmbus on i830
drm/i915: Replace the feature tests for BLT/BSD with ring init checks
drm/i915: Check whether the ring is initialised prior to dispatch
drm/i915: Introduce for_each_ring() macro
drm/i915: Assert that the transcoder is indeed off before modifying it
drm/i915: hook Haswell devices in place
drm/i915: prepare HDMI link for Haswell
drm/i915: move HDMI structs to shared location
drm/i915: add WR PLL programming table
drm/i915: add support for DDI-controlled digital outputs
drm/i915: detect digital outputs on Haswell
drm/i915: program iCLKIP on Lynx Point
drm/i915: program WM_LINETIME on Haswell
...
This should fix breakage introduced in
commit ee7b9f93fd
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date: Fri Apr 20 17:11:53 2012 +0100
drm/i915: manage PCH PLLs separately from pipes
v2: Add a DRM_DEBUG_KMS message to explain why a given pll was
selected, suggested by Chris Wilson.
v3: Actually run git add.
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49712
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Both the control and data registers are completely different now.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
- Changed the coding style of auxiliary infoframe functions to make
them smaller
- Fixed the column alignment of some function definitions
- Remove definition of "struct drm_crtc" in some places as they're
used only to retrieve "struct intel_crtc"
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
At least the worst offenders:
- SDVO specifies that the encoder should compute the ecc. Testing also
shows that we must not send the ecc field, so copy the dip_infoframe
struct to a temporay place and avoid the ecc field. This way the avi
infoframe is exactly 17 bytes long, which agrees with what the spec
mandates as a minimal storage capacity (with the ecc field it would
be 18 bytes).
- Only 17 when sending the avi infoframe. The SDVO spec explicitly
says that sending more data than what the device announces results
in undefined behaviour.
- Add __attribute__((packed)) to the avi and spd infoframes, for
otherwise they're wrongly aligned. Noticed because the avi infoframe
ended up being 18 bytes large instead of 17. We haven't noticed this
yet because we don't use the uint16_t fields yet (which are the only
ones that would be wrongly aligned).
This regression has been introduce by
3c17fe4b8f is the first bad commit
commit 3c17fe4b8f
Author: David Härdeman <david@hardeman.nu>
Date: Fri Sep 24 21:44:32 2010 +0200
i915: enable AVI infoframe for intel_hdmi.c [v4]
Patch tested on my g33 with a sdvo hdmi adaptor.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=25732
Tested-by: Peter Ross <pross@xvid.org> (G35 SDVO-HDMI)
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Hidden away within one chipset specific path was the necessary logic to
turn on the PLL. This needs to be done everywhere in order for us to
drive any display! As such as soon as we tested on a non-CougarPoint
chipset, we failed to bring up any DisplayPorts and generated a nice set
of assertion failures in the process. At least one part of our logic is
working, the part that assumes that we have no idea what we are doing.
Reported-by: guang.a.yang@intel.com
References: https://bugs.freedesktop.org/show_bug.cgi?id=49712
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Turn a fatal lockup into a merely blank display with lots of shouty
messages.
v2: Whilst in the area, convert the other BUG_ON into less fatal errors.
In particular, note that we may be called on a PCH platform not using
PLLs, such as Haswell, and so we do not always want to BUG_ON(!pll)
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
... we need it later on in the function to clean up pipe <-> plane
associations. This regression has been introduced in
commit f47166d2b0
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu Mar 22 15:00:50 2012 +0000
drm/i915: Sanitize BIOS debugging bits from PIPECONF
Spotted by staring at debug output of an (as it turns out) totally
unrelated bug.
v2: I've totally failed to do the s/pipe/i/ correctly, spotted by
Chris Wilson.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Cc: stable@kernel.org (the regression was Cc: stable, too)
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The hw just returns garbage.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49838
Reported-and-tested-by: Vladyslav <DFEW.Entwickler@googlemail.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
When userspace asks whether the driver supports the BLT or BSD rings for
this chip, simply report whether those particular rings are initialised
v2: Use intel_ring_initialized()
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Rather than use the magic feature tests HAS_BLT/HAS_BSD just check
whether the ring we are about to dispatch the execbuffer on is
initialised.
v2: Use intel_ring_initialized()
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
In many places we wish to iterate over the rings associated with the
GPU, so refactor them to use a common macro.
Along the way, there are a few code removals that should be side-effect
free and some rearrangement which should only have a cosmetic impact,
such as error-state.
Note that this slightly changes the semantics in the hangcheck code:
We now always cycle through all enabled rings instead of
short-circuiting the logic.
v2: Pull in a couple of suggestions from Ben and Daniel for
intel_ring_initialized() and not removing the warning (just moving them
to a new home, closer to the error).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
[danvet: Added note to commit message about the small behaviour
change, suggested by Ben Widawsky.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Inspired by a recent regression that seems to confuse pch transcoder
state, let's be a bit more paranoid.
References: https://bugs.freedesktop.org/show_bug.cgi?id=49712
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: Pimped commit message.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This patch enables i915 driver to handle Haswell devices. It should go in
last, when things are working stable enough.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
On Haswell, we need to properly train the DDI buffers prior to enabling
HDMI, and enable the required clocks with correct dividers for the desired
frequency.
Also, we cannot simple reuse HDMI routines from previous generations of
GPU, as most of HDMI-specific stuff is being done via the DDI port
programming instead of HDMI-specific registers.
This commit take advantage of the WR PLL clock table which is in a
separate (previous) commit to select the right divisors for each mode.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Move intel_hdmi data structure and support functions to a shared location,
to allow their usage from intel_ddi module.
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This table is used for programming WR PLL clocks, used by HDMI and DVI outputs.
I split it into a separate patch to simplify the HDMI enabling patch which was
getting huge.
Note that this table is a temporary solution for WR PLL programming. It
will be reworked into a more exact algorithm at a later stage. But for
now, it provides the most accurate clock setting solution, so we use it
here.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Those are driven by DDIs on Haswell architecture, so we need to keep track
of which DDI is being used on each output.
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Digital port detection on Haswell is indicated by the presence of a bit in
DDI_BUF_CTL for port A, and by a different register for ports B, C and D.
So we check for those bits during the initialization time and let the hdmi
function know about those.
Note that this bit does not indicates whether the output is DP or HDMI.
However, the DDI buffers can be programmed in a way that is shared between
DP/HDMI and FDI/HDMI except for PORT E.
So for now, we detect those digital outputs as being HDMI, but proper DP
support is still pending.
Note that DDI A can only drive eDP, so we do not handle it here for hdmi
initialization.
v2: simplify Haswell handling logic
v3: use generic function for handling digital outputs.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The iCLKIP clock is used to drive the VGA pixel clock on the PCH. In order
to do so, it must be programmed to properly do the clock ticks according
to the divisor, phase direction, phase increments and a special auxiliary
divisor for 20MHz clock.
v2: calculate divisor values directly instead of relying on a table.
v3: merged a fix from Ben to properly check for invalid divider values.
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The line time can be programmed according to the number of horizontal
pixels vs effective pixel rate ratio.
v2: improve comment as per Chris Wilson suggestion
v3: incorporate latest changes in specs.
v4: move into wm update routine, also mention that the same routine can
program IPS watermarks. We do not have their enablement code yet, nor
handle the required clock settings at the moment, so this patch won't
program those values for now.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
For now, we simple reuse the Ivy Bridge routines here.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Starting with Haswell, DDI ports can work in FDI mode to support
connectivity with the outputs located on the PCH.
This commit adds support for such connections in the intel_ddi module, and
provides Haswell-specific functionality to make it work.
v2: simplify the commit as per Daniel Vetter suggestion.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
DDI is introduced starting with Haswell GPU generation. So to simplify its
management in the future, we also add intel_ddi.c to hold all the
DDI-related items.
Buffer translations for DDI links must be initialized prior to enablement.
For FDI and DP, first 9 pairs of values are used to select the connection
parameters. HDMI uses the last pair of values and ignores the first 9
pairs. So we program HDMI values in both cases, which allows HDMI to work
over both FDI and DP-friendly buffers.
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
On Haswell, only one pipe can work in FDI mode, so this patch prevents
messing with wrong registers when FDI is being used by non-first pipe. And
to prevent this, we also specify that the VGA can only be used on pipe 0
for now in the crtc_mask value.
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Prevent bogus asserts on DDI-related paths.
Longer explanation from Eugeni by mail:
"For the asserts there are 3 paths where we hit them:
- in assert_fdi_tx (we don't have the FDI_TX_CTL anymore, backup plan
DDI_FUNC_CTL is used instead)
- in assert_fdi_tx_pll_enabled (we have the combination of iCLKIP and
DDI_FUNC_CTL, plus PORT_CLK_SEL and PIPE_CLK_SEL now to make things
work). We could use an assert here indeed - if we configure port to
use one clock, and pipe to use another, everything hangs. Right now,
we configure all of them in one place only; but yes, when DP code
lands it will get more funky.
- and in ironlake_fdi_pll_enable. I reuse part of this function (to
configure the TU sizes), but as in the 1st case, FDI_TX_CTL is gone
so I just ignore it here."
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
[danvet: Pasted Eugeni's explanation into the commit message.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This attempts to enable all the available power wells during the
initialization.
Those power wells can be enabled in parallel or on-demand, and disabled
when no longer needed, but this is out of scope of this initial
enablement. Proper tracking of who uses which power well will require
a considerable rework of our display handling, so we just leave them all
enabled when the driver is loaded for now.
v2: use more generic and future-proof code
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
On Haswell, the recommended PCH-connected output is the one driven by DDI
E in FDI mode, used for VGA connection. All the others are handled by the
CPU.
Note that this does not accounts for Haswell/PPT combination yet, so if we
encounter such combination an error message is thrown to indicate that
things could go wrong.
v2: improve non-LPT detection warning per Daniel Vetter's suggestion.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This should be already configured when FDI auto-negotiation is done.
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This will throw a BUG() message when an unknown sdvox register is
given to intel_hdmi_init. When this happens, things could going to be pretty
much broken afterwards, so we better detect this as soon as possible.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
As suggested by Chris Wilson and Daniel Vetter, this chunk of code can be
simplified with a more simple check.
Also, as noticed by Jesse Barnes, it is worth mentioning that plane is an
enum and num_pipe is an int, so we could be more paranoid here about those
validation checks eventually.
CC: Daniel Vetter <daniel.vetter@ffwll.ch>
CC: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This adds proper support for calculating those watermarks, checking for
number of available pipes instead of specific GPU variants when deciding
if watermarks for 3rd pipe are necessary.
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
With Lynx Point, we need to use SBI to communicate with the display clock
control. This commit adds helper functions to access the registers via
SBI.
v2: de-inline the function and address changes in bits names
v3: protect operations with dpio_lock, increase timeout to 100 for
paranoia sake.
v4: decrease paranoia a bit, as noticed by Chris Wilson
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Haswell interrupts are mostly similar with Ivy Bridge, so we share same
routines with it.
This patch also simplifies the vblank counter handling for all the Gen5+
architectures.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Haswell has different DIP control registers and offsets which we need to
use for infoframes, which this patch adds.
Note that this does not adds full DIP frames support, but only the basic
functionality necessary for HDMI to work in early enablement.
v2: replace infoframe handling with a debug message, proper support will
be added via a patch from Paulo Zanoni later.
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Reviewed-by: Paulo Zanoni <przanoni@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Currently we call gen6_enable_rps() (which writes into the per-ring
register mmio space) from intel_modeset_init_hw() which is called before
we initialise the rings. If we defer intel_modeset_init_hw() until
afterwards (in the intel_modeset_gem_init() phase) all is well.
v2: Rectify ordering of gem vs display HW init upon resume. (Daniel)
v3: Fix up locking. (Paulo)
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: Smash Paulo's locking fix onto Chris' patch.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This lets the kernel tell userspace if the device supports prime
import/export.
This is useful for -modesetting at least, but would be nice for other
drivers.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>
