[alsa-devel] [PATCH 2/2] ALSA: hda - get realtime ELD info when codec suspended

Wang Xingchao wangxingchao2011 at gmail.com
Fri Jul 12 08:13:44 CEST 2013

Hi David/Takashi,

Here's some update on this topic.
I used evtest to monitor hotplug input event for Headphone, it doesnot
report the hotplug event when audio controller/codec in runtime
suspend mode.
if it's during audio playback(both controller and codec are active),
the events could be monitored correctly.
However even the controller/codec in runtime suspend mode, the hotplug
event was not missed when waken up from suspend mode. After exit from
suspend mode, the hotplug event would be reported asap.
So userspace will not receive the event notification from driver when
controller/codec in suspend mode, but it will get them once audio
controller/codec become active.
I think it's acceptable for audio playback functinality, it will not
harm audio routing in fact. i'm not sure there's other potential risk,
i.e. user space will show/hide the devices in UI according to the
event, in that case , user will never see the Headphone device for
playback before audio controller/codec was waken up in another way.

Meanwhile i tested attached patch to monitor WAKEEN events, it doesnot
work well as Spec said. it would not wake up audio controller/codec
when plug in/out headphone in runtime suspend mode, and the status
register always be 0.


2013/6/25 David Henningsson <david.henningsson at canonical.com>:
> On 06/25/2013 11:33 AM, Wang, Xingchao wrote:
>> Hi David,
>>> -----Original Message-----
>>> From: alsa-devel-bounces at alsa-project.org
>>> [mailto:alsa-devel-bounces at alsa-project.org] On Behalf Of David
>>> Henningsson
>>> Sent: Tuesday, June 25, 2013 5:02 PM
>>> To: Wang, Xingchao
>>> Cc: Takashi Iwai; alsa-devel at alsa-project.org
>>> Subject: Re: [alsa-devel] [PATCH 2/2] ALSA: hda - get realtime ELD info
>>> when
>>> codec suspended
>>> On 06/25/2013 09:55 AM, Takashi Iwai wrote:
>>>> At Tue, 25 Jun 2013 09:45:04 +0200,
>>>> David Henningsson wrote:
>>>>>> There is a low power mode that allows the jack detection, but this
>>>>>> is different from the aggressive power-saving with runtime D3.
>>>>> If "aggressive power-saving with runtime D3" is the same as
>>>>> AZX_DCAPS_PM_RUNTIME, this is also enabled for analog codecs
>>>>> connected to a Lynx point controller.
>>>>> It looks like userspace have problems getting notifications for e g
>>>>> headphone insertion on Lynx point controllers, so this is not only an
>>>>> HDMI/DP problem?
>>>> Yes.
>>>>> Trying to read up a little on this, there seem to be an option to set
>>>>> the WAKEEN register to have jack detection working even when the
>>>>> controller is in D3. (refer HDA specification
>>>>> Codec Wake From System S0, Controller D3.) But it seems we do not
>>>>> (yet) use this feature. Is this something that could/should be
>>>>> implemented to fix the jack detection problems that seems to be
>>>>> happening otherwise?
>>>> It sounds feasible, at least for traditional jack detection of analog
>>>> pins.  But I'm not sure whether this would help for the Intel graphics
>>>> case.  Just need testing.
>>> Xingchao, what are your thoughts about using WAKEEN to wakeup both Lynx
>>> point and Haswell HDMI?
>> That's okay for me, I would do some test on that. do you have some test
>> cases?
>> That would help me verify them when enable WAKEEN feature.
> Since we still enable the legacy jack feature through /dev/input/event*, the
> easiest way to test would probably to run evtest (which is in the Ubuntu
> repositories). Find the correct /dev/input/event file by checking dmesg (or
> just trying them one by one), then run "sudo evtest /dev/input/<filename>".
> Now check if you get events correctly on HDMI/DP/Headphone/Mic/etc plug and
> unplug, even if the controller is runtime suspended.
> Also note that WAKEEN should probably be disabled during system S3, because
> we don't want to wake up the entire computer just because somebody unplugs
> his headphone, right?
> --
> David Henningsson, Canonical Ltd.
> https://launchpad.net/~diwic
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel at alsa-project.org
> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-ALSA-hda-Enable-WAKEEN-for-codecs-blindly-for-test.patch
Type: application/octet-stream
Size: 1588 bytes
Desc: not available
URL: <http://mailman.alsa-project.org/pipermail/alsa-devel/attachments/20130712/6fc4ac88/attachment.obj>

More information about the Alsa-devel mailing list