[alsa-devel] [PATCH v2] ALSA: hda - Fix Skylake codec timeout

[Yang, Libin]

Hi Takashi,

> -----Original Message-----
> From: Takashi Iwai [mailto:tiwai at suse.de]
> Sent: Friday, July 17, 2015 9:02 PM
> To: Yang, Libin
> Cc: David Henningsson; hui.wang at canonical.com; alsa-devel at alsa-
> project.org; Lin, Mengdong; Lu, Han
> Subject: Re: [PATCH v2] ALSA: hda - Fix Skylake codec timeout
> 
> On Fri, 17 Jul 2015 04:28:10 +0200,
> Yang, Libin wrote:
> >
> >
> > > -----Original Message-----
> > > From: Takashi Iwai [mailto:tiwai at suse.de]
> > > Sent: Thursday, July 16, 2015 11:54 PM
> > > To: David Henningsson
> > > Cc: Yang, Libin; hui.wang at canonical.com; alsa-devel at alsa-
> project.org;
> > > Lin, Mengdong; Lu, Han
> > > Subject: Re: [PATCH v2] ALSA: hda - Fix Skylake codec timeout
> > >
> > > On Thu, 16 Jul 2015 17:37:41 +0200,
> > > David Henningsson wrote:
> > > >
> > > >
> > > >
> > > > On 2015-07-16 17:34, Takashi Iwai wrote:
> > > > > On Thu, 16 Jul 2015 17:31:33 +0200,
> > > > > David Henningsson wrote:
> > > > >>
> > > > >>
> > > > >>
> > > > >> On 2015-07-16 17:14, Yang, Libin wrote:
> > > > >>>> -----Original Message-----
> > > > >>>> From: David Henningsson
> > > [mailto:david.henningsson at canonical.com]
> > > > >>>> Sent: Thursday, July 16, 2015 4:39 PM
> > > > >>>> To: tiwai at suse.de; hui.wang at canonical.com; alsa-
> devel at alsa-
> > > > >>>> project.org; Yang, Libin; Lin, Mengdong
> > > > >>>> Cc: David Henningsson
> > > > >>>> Subject: [PATCH v2] ALSA: hda - Fix Skylake codec timeout
> > > > >>>>
> > > > >>>> When the controller is powered up but the HDMI codec is
> > > powered
> > > > >>>> down
> > > > >>>> on Skylake, the power well is turned off. When the codec is
> > > then
> > > > >>>> powered up again, we need to poke the codec a little extra
> to
> > > make
> > > > >>>> sure it wakes up. Otherwise we'll get sad "no response
> from
> > > codec"
> > > > >>>> messages and broken audio.
> > > > >>>
> > > > >>> Thanks for finding this issue.
> > > > >>>
> > > > >>> Could you please give us you test case? We didn't meet such
> > > issue
> > > > >>> before. I would like do a full test on it.
> > > > >>
> > > > >> The test case is:
> > > > >>
> > > > >>    - Install Ubuntu 15.04.
> > > > >>    - Upgrade to kernel 4.1.
> > > > >>    - Boot the new kernel.
> > > > >>
> > > > >> Note: I believe Hui tested with 4.1 and got this error. In my
> case I
> > > > >> have been running a hybrid kernel: Ubuntu 15.04, kernel
> 3.19.0-
> > > 23.24
> > > > >> (which has a backported i915 driver), and then the alsa-daily
> > > DKMS on
> > > > >> top of that.
> > > > >>
> > > > >> I can email you off-list with details about the machine I tested
> it
> > > on,
> > > > >> if you like.
> > > > >
> > > > > Did you hotplug the device or is it booted while plugged?
> > > > > I had an unstable communication at hotplug / unplug on SKL at
> the
> > > last
> > > > > time, too.  But the boot with the DP plugged worked well even
> on
> > > an
> > > > > old SKL box.
> > > >
> > > > For this bug, there was no HDMI monitor connected at all, but I
> > > believe
> > > > it does not matter. On power up, the power well is enabled and
> then
> > > > disabled. When the power well is enabled again without this
> extra
> > > wakeup
> > > > poke (probably due to PulseAudio probing), this error happens.
> > >
> > > Ah, that's interesting.  So this happens when no monitor is
> > > connected.  I haven't seen this, though; maybe depends on the
> board
> > > or
> > > BIOS.
> >
> > On SKL, each time turning on power well 2, display codec need
> > extra wakeup poke.
> >
> > If there is monitor connected, power well will not be turned
> > off even audio driver asks to.
> >
> > If there is monitor connected, power well will be really
> > turned off. In this case, when hdmi audio is used, we
> > must do the wakeup poke.
> 
> So the patch does the right thing?  I'm currently waiting for an ack
> from you Intel people as this is highly specific to the chipset
> detail.  Please give reviewed-by, acked-by or whatever if the patch is
> OK.

The patch is right. I have reviewed the patch and Our QA has verified it.

> 
> 
> thanks,
> 
> Takashi