[alsa-devel] [PATCH] ALSA: hda_intel: add AZX_DCAPS_I915_POWERWELL for skl

[Takashi Iwai]

At Fri, 27 Mar 2015 08:25:52 +0000,
Yang, Libin wrote:
> 
> Hi Takashi,
> 
> 
> > -----Original Message-----
> > From: alsa-devel-bounces at alsa-project.org [mailto:alsa-devel-
> > bounces at alsa-project.org] On Behalf Of Takashi Iwai
> > Sent: Friday, March 27, 2015 4:19 PM
> > To: Yang, Libin
> > Cc: alsa-devel at alsa-project.org
> > Subject: Re: [alsa-devel] [PATCH] ALSA: hda_intel: add
> > AZX_DCAPS_I915_POWERWELL for skl
> > 
> > At Fri, 27 Mar 2015 08:02:54 +0000,
> > Yang, Libin wrote:
> > >
> > > Hi Takashi,
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Takashi Iwai [mailto:tiwai at suse.de]
> > > > Sent: Friday, March 27, 2015 3:57 PM
> > > > To: Yang, Libin
> > > > Cc: alsa-devel at alsa-project.org
> > > > Subject: Re: [PATCH] ALSA: hda_intel: add
> > > > AZX_DCAPS_I915_POWERWELL for skl
> > > >
> > > > At Fri, 27 Mar 2015 15:10:04 +0800,
> > > > libin.yang at intel.com wrote:
> > > > >
> > > > > From: Libin Yang <libin.yang at intel.com>
> > > > >
> > > > > HDMI/DP codec on SKL is in the power well.
> > > > > The power well must be turned on before probing the
> > > > > HDMI/DP codec.
> > > > >
> > > > > Signed-off-by: Libin Yang <libin.yang at intel.com>
> > > >
> > > > So, was the previous question clarified?
> > >
> > > Yes, I have confirmed with our silicon team.
> > >
> > > >
> > > > This certainly sucks.  It means that the powerwell is on even you
> > > > don't use the HDMI/DP at all.  If this is intended as a temporarily
> > > > workaround, it should be mentioned so.  Please give more
> > comments
> > > > and
> > > > backgrounds.
> > >
> > > Yes, as this is added in the skl audio controller, even there is no
> > HDMI/DP
> > > codec, we should also add this flag. Otherwise the HDMI/DP codec
> > > may not be detected correctly.
> > 
> > But it's possible to do it only at probing, not permanently.  If so,
> > we'll have another patch in future.
> > 
> > Please write more information in the changelog and resubmit.
> 
> Do you mean to add more description in the patch comments?

Yes.  The hardware design is different from HSW/BDW, thus applying
this isn't straightforward but just a workaround.  I don't know
whether you think it's a temporary workaround or a permanent fix.
Such information must be written there, too.


Takashi