Back in 2013, runtime PM for GPUs with integrated HDA controller was
introduced with commits 0d69704ae3 ("gpu/vga_switcheroo: add driver
control power feature. (v3)") and 246efa4a07 ("snd/hda: add runtime
suspend/resume on optimus support (v4)").
Briefly, the idea was that the HDA controller is forced on and off in
unison with the GPU.
The original code is mostly still in place even though it was never a
100% perfect solution: E.g. on access to the HDA controller, the GPU
is powered up via vga_switcheroo_runtime_resume_hdmi_audio() but there
are no provisions to keep it resumed until access to the HDA controller
has ceased: The GPU autosuspends after 5 seconds, rendering the HDA
controller inaccessible.
Additionally, a kludge is required when hda_intel.c probes: It has to
check whether the GPU is powered down (check_hdmi_disabled()) and defer
probing if so.
However in the meantime (in v4.10) the driver core has gained a feature
called device links which promises to solve such issues in a clean way:
It allows us to declare a dependency from the HDA controller (consumer)
to the GPU (supplier). The PM core then automagically ensures that the
GPU is runtime resumed as long as the HDA controller's ->probe hook is
executed and whenever the HDA controller is accessed.
By default, the HDA controller has a dependency on its parent, a PCIe
Root Port. Adding a device link creates another dependency on its
sibling:
PCIe Root Port
^ ^
| |
| |
HDA ===> GPU
The device link is not only used for runtime PM, it also guarantees that
on system sleep, the HDA controller suspends before the GPU and resumes
after the GPU, and on system shutdown the HDA controller's ->shutdown
hook is executed before the one of the GPU. It is a complete solution.
Using this functionality is as simple as calling device_link_add(),
which results in a dmesg entry like this:
pci 0000:01:00.1: Linked as a consumer to 0000:01:00.0
The code for the GPU-governed audio power management can thus be removed
(except where it's still needed for legacy manual power control).
The device link is added in a PCI quirk rather than in hda_intel.c.
It is therefore legal for the GPU to runtime suspend to D3cold even if
the HDA controller is not bound to a driver or if CONFIG_SND_HDA_INTEL
is not enabled, for accesses to the HDA controller will cause the GPU to
wake up regardless if they're occurring outside of hda_intel.c (think
config space readout via sysfs).
Contrary to the previous implementation, the HDA controller's power
state is now self-governed, rather than GPU-governed, whereas the GPU's
power state is no longer fully self-governed. (The HDA controller needs
to runtime suspend before the GPU can.)
It is thus crucial that runtime PM is always activated on the HDA
controller even if CONFIG_SND_HDA_POWER_SAVE_DEFAULT is set to 0 (which
is the default), lest the GPU stays awake. This is achieved by setting
the auto_runtime_pm flag on every codec and the AZX_DCAPS_PM_RUNTIME
flag on the HDA controller.
A side effect is that power consumption might be reduced if the GPU is
in use but the HDA controller is not, because the HDA controller is now
allowed to go to D3hot. Before, it was forced to stay in D0 as long as
the GPU was in use. (There is no reduction in power consumption on my
Nvidia GK107, but there might be on other chips.)
The code paths for legacy manual power control are adjusted such that
runtime PM is disabled during power off, thereby preventing the PM core
from resuming the HDA controller.
Note that the device link is not only added on vga_switcheroo capable
systems, but for *any* GPU with integrated HDA controller. The idea is
that the HDA controller streams audio via connectors located on the GPU,
so the GPU needs to be on for the HDA controller to do anything useful.
This commit implicitly fixes an unbalanced runtime PM ref upon unbind of
hda_intel.c: On ->probe, a runtime PM ref was previously released under
the condition "azx_has_pm_runtime(chip) || hda->use_vga_switcheroo", but
on ->remove a runtime PM ref was only acquired under the first of those
conditions. Thus, binding and unbinding the driver twice on a
vga_switcheroo capable system caused the runtime PM refcount to drop
below zero. The issue is resolved because the AZX_DCAPS_PM_RUNTIME flag
is now always set if use_vga_switcheroo is true.
For more information on device links please refer to:
https://www.kernel.org/doc/html/latest/driver-api/device_link.html
Documentation/driver-api/device_link.rst
Cc: Dave Airlie <airlied@redhat.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Peter Wu <peter@lekensteyn.nl>
Tested-by: Kai Heng Feng <kai.heng.feng@canonical.com> # AMD PowerXpress
Tested-by: Mike Lothian <mike@fireburn.co.uk> # AMD PowerXpress
Tested-by: Denis Lisov <dennis.lissov@gmail.com> # Nvidia Optimus
Tested-by: Peter Wu <peter@lekensteyn.nl> # Nvidia Optimus
Tested-by: Lukas Wunner <lukas@wunner.de> # MacBook Pro
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://patchwork.freedesktop.org/patch/msgid/51bd38360ff502a8c42b1ebf4405ee1d3f27118d.1520068884.git.lukas@wunner.de
Currently everyone and their dog has their own favourite spelling
for vga_switcheroo. This makes it hard to grep dmesg for log entries
relating to vga_switcheroo. It also makes it hard to find related
source files in the tree.
vga_switcheroo.c uses pr_fmt "vga_switcheroo". Use that everywhere.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: http://patchwork.freedesktop.org/patch/msgid/9b0175319ce78d831acfcf11e4c6c760f826b0e3.1444663039.git.lukas@wunner.de
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The file is moved to hda core and renamed to hdac_i915.c, so can be used
by both legacy HDA driver and new Skylake audio driver.
- Add snd_hdac_ prefix to the public APIs.
- The i915 audio component is moved to core bus and dynamically allocated.
- A static pointer hdac_acomp is used to help bind/unbind callbacks to get
this component, because the sound card's private_data is used by the azx
chip pointer, which is a legacy structure. It could be removed if private
_data changes to some core structure which can be extended to find the
bus.
- snd_hdac_get_display_clk() is added to get the display core clock for
HSW/BDW.
- haswell_set_bclk() is moved to hda_intel.c because it needs to write the
controller registers EM4/EM5, and only legacy HD-A needs it for HSW/BDW.
- Move definition of HSW/BDW-specific registers EM4/EM5 to hda_register.h
and rename them to HSW_EM4/HSW_EM5, because other HD-A controllers have
different layout for the extended mode registers.
Signed-off-by: Mengdong Lin <mengdong.lin@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
In SKL, HDMI/DP codec and PCH HD Audio Controller are in different power wells,
so it's necessary to reset display audio codecs when power well on, otherwise
display audio codecs will disappear when resume from low power state.
Reset steps when power on:
enable codec wakeup -> azx_init_chip() -> disable codec wakeup
The callback for codec wakeup enable/disable is in drivers/gpu/drm/i915/.
Signed-off-by: Lu, Han <han.lu@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
We're providing dummy functions for CONFIG_SND_HDA_i915=n, thus ifdef
can be reduced. (But hda_i915_init() has to be fixed to return zero.)
This automatically fixes a compile warning:
sound/pci/hda/hda_intel.c: In function 'azx_probe_continue':
sound/pci/hda/hda_intel.c:1966:1: warning: label 'i915_power_fail' defined but not used [-Wunused-label]
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This patch can improve power saving for Intel platforms on which only the
display audio codec is in the shared i915 power well:
- Add a flag "need_i915_power" to indicate whether the controller needs the
i915 power well.
- The driver will always request the i915 power when probing the controller
and codecs if AZX_DCAPS_I915_POWERWELL is set (either the controller or a
codec needs this power).
- If the controller needs the i915 power, the power will be held after probe
until the controller is runtime suspended or S3. If the controller doesn't
need the power, the power will be released the after probe, and a codec
that needs the power can request/release the power via bus link_power ops.
Background:
- For Haswell/Broadwell, which has a separate HD-A controller for display audio,
both the controller and the display codec are in the i915 power well.
- For Baytrail/Braswell, the display and analog audio share the same HDA
controller and link, and only the display codec is in the i915 power well.
- For Skylake, the display and analog audio share the same HDA controller but
use separate links. Only the display codec is in the i915 power well. And in
legacy mode we take the two links as one. So it can follow Baytrail/Braswell.
Signed-off-by: Mengdong Lin <mengdong.lin@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This is to check the refcount of audio driver and reduce calling to i915.
Signed-off-by: Mengdong Lin <mengdong.lin@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
... and replace with the existing hda-core helper codes.
This reduces lots of lines, finally.
Since struct hda_bus is now embedded into struct azx,
snd_hda_bus_new() is moved and expanded from hda_codec.c to
hda_controller.c, accordingly. Also private_free bus ops and
private_data field are removed because we no longer need to point azx
object from bus (we can use container_of())
The spin locks are consolidated into the single one, bus->reg_lock.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Register a component master to be used to interface with the i915
driver. This is meant to replace the current interface which is based on
module symbol lookups.
Note that currently we keep the existing behavior and pin the i915
module while the hda driver is loaded. Using the component interface
allows us to remove this dependency once support for dynamically
enabling / disabling the HDMI functionality is added to the driver.
v2:
- change roles between the hda and i915 components (Daniel)
v3:
- rename display_component to audio_component (Daniel)
v4:
- move removal of i915_powerwell.h from this patch to the next (Takashi)
- request_module fails if module support isn't enabled, so ignore
any error it returns and depend on the following NULL check of the
component ops (Takashi)
- change over to using dev_* instead of pr_* (Takashi)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
chip is already passed to most of the i915 interface functions. Unify
the interface by passing intel_hda instead of chip and passing it to all
functions. Passing intel_hda instead of chip makes more sense since this
is an intel specific interface. Also in an upcoming patch we will use
intel_hda in all of these functions so by passing intel_hda we can save
on some pointer casts from chip to intel_hda.
This will be needed by an upcoming patch adding component support.
No functional change.
v2-3: unchanged
v4:
- pass intel_hda instead of chip
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This struct will be needed by the component code added in an upcoming
patch, so export it into a new hda_intel.h file. At the same time also
merge hda_i915.h into this new header, there is no reason to keep two
separate intel specific header file.
Suggested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
