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

[Takashi Iwai]

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.


Takashi