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

[David Henningsson <david.henningsson@canonical.com>]

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@canonical.com]
>>>> Sent: Thursday, July 16, 2015 4:39 PM
>>>> To: tiwai@suse.de; hui.wang@canonical.com; alsa-devel@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.

-- 
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic