[alsa-devel] [PATCH] drm/i915: Add private api for power well usage -- alignment between graphic team and audio team

Takashi Iwai tiwai at suse.de
Fri May 3 16:31:34 CEST 2013

At Fri, 03 May 2013 14:02:04 +0200,
David Henningsson wrote:
> On 05/03/2013 10:28 AM, Wang, Xingchao wrote:
> > Hi David,
> >
> > Thank you very much for your draft patch.
> > I have some more work on a new patchset, some ideas are from your patch.
> Thanks.
> > Here's a brief introduction of attached patchset:
> >
> > 1. a new bus type in /sound/had_bus.c, used to bind the single module and codec device
> > It looks like ac97_bus.c
> I don't understand why this is needed. It does not look like it's used 
> from the gfx side either, or anything like that?
> > 2. add a new device node in "struct hda_codec", it's used to register for new bus type.
> >
> > 3. a new single module hdmi_i915, which compiled in only when DRM_I915 and CODEC_HDMI enabled.
> > It stores the private API for gfx part.
> > There's no support to probe haswell hdmi codec only yet. Power well will be used only for haswell display audio.
> >
> > 4. power well API implementation in gfx side.
> >
> > Please feel free to add your idea and I will help test your patch too.
> Ok. So the patch I wrote would (if it works) be combined with your patch 
> 3, which implements the gfx side. The gfx side is not my area of expertise.
> The proposed way in my patch would be more elegant since it does not 
> introduce any i915 related code in hda_codec* files.
> Still, Takashi is the boss here so he has the final say :-)

Indeed.  If the reference to power well API is limited in a newly
split snd-hda-codec-hdmi-i915 driver, we don't have to create yet
another driver instance.  The snd-hda-codec-hdmi-i915 can simply
depend on i915, by referring to a symbol exported from i915 driver.

If we now touch the whole PM sequence in both gfx and audio drivers
(i.e. it influences on the HD-audio controller code, hda_intel.c),
then we may need a different management.  But I thought it's not yet
discussed here, right?


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