Hi all, Please find attached document, which could help guys get some background information in case you donot have intel haswell test boards. thanks --xingchao > -----Original Message----- > From: alsa-devel-bounces at alsa-project.org > [mailto:alsa-devel-bounces at alsa-project.org] On Behalf Of Wang Xingchao > Sent: Monday, May 13, 2013 3:37 PM > To: tiwai at suse.de; daniel at ffwll.ch; Girdwood, Liam R > Cc: alsa-devel at alsa-project.org; Zanoni, Paulo R; Li, Jocelyn; Lin, Mengdong; > intel-gfx at lists.freedesktop.org; Wang Xingchao; Barnes, Jesse; > david.henningsson at canonical.com > Subject: [alsa-devel] [PATCH 0/5] Power-well API implementation for Haswell > > This patchset intended to Add power-well api support for Haswell. > > For Intel Haswell , ?power well? in GPU has impact for both Display HD-A > controller and codecs. Gfx driver has power well feature enaled but donot think > much about audio side. The issue is if gfx driver disabled power well, audio side > would lose power and crash. > > David helped a initial patch to add external module patch_hdmi_i915, which > built in only DRM_I915 and HDMI_CODEC enabled, This patchset was based > on David?s work, thanks David! > > As codec depends on controller?s power, so we removed the pm callback > temporary. So only HDA controller driver would such need to request/release > power, the codec will always be safe. > > Gfx driver would shutdown power well in below cases, audio driver would be > damaged as losing power totally without any notification. > (There would be more cases not covered, welcome more comments here. > i can verify the patchset under more cases) > - Only eDP port active > - HDMI monitor hot plug > - System suspend > > Also there?re some calling from i915 to disable power well from time to time, > this patchset would reject those operations if audio using power well, but it will > record i915 driver?s request and shut down power if audio release it. > > Basically, here's the latest working status on my side: > > I tested the power well feature on Haswell ULT board, there's only one eDP > port used. Without this patch and we enabled power well feature, gfx driver > will shutdown power well, audio driver will crash. > Applied this patch, display audio driver will request power well on before > initialize the card. In gfx side, it will enable power well. > > Also power_save feature in audio side should be enabled, I set "5" second to let > codec enter suspend when free for 5s long. > Audio controller driver detects all codecs are suspended it will release power > well and suspend too. Gfx driver will receive the request and shut down power > well. > > If user trigger some audio operations(cat codec# info), audio controller driver > will request power well again... > > If gfx side decided to disable power well now, while audio is in use, power well > would be kept on. > > (i will send out a documentation which has some logs and analysis there.) > > Generally audio drvier will request power well on need and release it > immediately after suspend. Gfx should make decision at his side. > > The new introduced module "hda-i915" has dependency on i915, only built in > when i915 enabled. So it's safe for call. > > For non-Haswell platform, power well is no need atm. Even the module is built > in wrongly, hda driver will not call the power well api. Also gfx will reject power > well request at its side, so it's safe too. > > This patch could make sure it would not cause damage when snd-hda-intel and > i915 module loaded in any order. If i915 module loaded at first, it's safe to get > the symbol. If snd-hda-intel loaded first, it will try to load i915 manually and get > notification when the power-well api are exported. > > Wang Xingchao (5): > drm/915: Add private api for power well usage > ALSA: hda - Add external module hda-i915 for power well > ALSA: hda - Power well request/release for hda controller > ALSA: hda - Fix module dependency with gfx i915 > ALSA/i915: Check power well API existense before calling > > drivers/gpu/drm/i915/i915_dma.c | 3 + > drivers/gpu/drm/i915/intel_drv.h | 2 + > drivers/gpu/drm/i915/intel_pm.c | 139 > ++++++++++++++++++++++++++++++++++++-- > include/drm/i915_powerwell.h | 40 +++++++++++ > sound/pci/hda/Kconfig | 13 ++++ > sound/pci/hda/Makefile | 6 ++ > sound/pci/hda/hda_i915.c | 92 +++++++++++++++++++++++++ > sound/pci/hda/hda_i915.h | 15 ++++ > sound/pci/hda/hda_intel.c | 22 ++++++ > 9 files changed, 325 insertions(+), 7 deletions(-) create mode 100644 > include/drm/i915_powerwell.h create mode 100644 > sound/pci/hda/hda_i915.c create mode 100644 sound/pci/hda/hda_i915.h > > -- > 1.7.9.5 > > _______________________________________________ > Alsa-devel mailing list > Alsa-devel at alsa-project.org > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel -------------- next part -------------- A non-text attachment was scrubbed... Name: power-well-api-upstream.pdf Type: application/pdf Size: 472307 bytes Desc: power-well-api-upstream.pdf URL: <http://lists.freedesktop.org/archives/intel-gfx/attachments/20130513/fc60eeeb/attachment-0001.pdf>
