Re: [PATCH 2/2] drm/amd/display: Add drm_audio_component support to amdgpu_dm

[Takashi Iwai <tiwai-l3A5Bk7waGM@public.gmane.org>]

On Wed, 17 Jul 2019 15:32:55 +0200,
Takashi Iwai wrote:
> 
> On Wed, 10 Jul 2019 16:36:19 +0200,
> Takashi Iwai wrote:
> > 
> > On Wed, 10 Jul 2019 16:31:40 +0200,
> > Kazlauskas, Nicholas wrote:
> > > 
> > > On 7/10/19 9:48 AM, Takashi Iwai wrote:
> > > > On Tue, 09 Jul 2019 18:30:19 +0200,
> > > > Nicholas Kazlauskas wrote:
> > > >>
> > > >> [Why]
> > > >> The drm_audio_component can be used to give pin ELD notifications
> > > >> directly to the sound driver. This fixes audio endpoints disappearing
> > > >> due to missing unsolicited notifications.
> > > >>
> > > >> [How]
> > > >> Send the notification via the audio component whenever we enable or
> > > >> disable audio state on a stream. This matches what i915 does with
> > > >> their drm_audio_component and what Takashi Iwai's proposed hack for
> > > >> radeon/amdpgu did.
> > > >>
> > > >> This is a bit delayed in when the notification actually occurs, however.
> > > >> We wait until after all the programming is complete rather than sending
> > > >> the notification mid sequence.
> > > >>
> > > >> Particular care is needed for the get ELD callback since it can happen
> > > >> outside the locking and fencing DRM does for atomic commits.
> > > >>
> > > >> Cc: Takashi Iwai <tiwai@suse.de>
> > > >> Cc: Leo Li <sunpeng.li@amd.com>
> > > >> Cc: Harry Wentland <harry.wentland@amd.com>
> > > >> Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
> > > > 
> > > > Thanks for the patch, this has been a long-standing TODO for me, too!
> > > > 
> > > > Do you have the patch for HD-audio part as well?  Or you tested with
> > > > my old patch?  Then I'll resurrect my patch set as well.
> > > 
> > > I've tested this series with and without that patch. The notifications 
> > > work and the driver will query back with get_eld as expected.
> > 
> > OK, then I'm going to prepare a branch including that patch.
> 
> FWIW, my latest patches are found in topic/hda-acomp branch on sound
> git tree:
>   git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git topic/hda-acomp
> 
> There have been a slight refactoring in HD-audio side, and now it
> supports both AMD and Nvidia audio component support.  The branch
> contains the patches for radeon and nouveau support.
> 
> Note that the branch isn't permanent one, it'll be rebased later.
> Once after I submit and get the review for the HD-audio patches, I'll
> create an immutable branch based on 5.3-rc1 containing those HD-audio
> patches (but not DRM ones), so that you can pull into your drm tree
> for the completeness.

BTW, one thing I forgot to add: i915 audio component recently added
the device-link for assuring the PM call order.  More specifically, in
the component bind and unbind callbacks, device_link_add() and
device_link_del() get called respectively.  I guess the similar calls
are needed for AMDGPU driver as well.


thanks,

Takashi
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