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

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

On 06/24/2013 03:00 PM, Takashi Iwai wrote:
> At Mon, 24 Jun 2013 14:47:01 +0200,
> David Henningsson wrote:
>>
>> On 06/24/2013 02:00 PM, Takashi Iwai wrote:
>>> At Mon, 24 Jun 2013 11:56:21 +0000,
>>> Wang, Xingchao wrote:
>>>>
>>>>> -----Original Message-----
>>>>> From: Takashi Iwai [mailto:tiwai@suse.de]
>>>>> Sent: Monday, June 24, 2013 7:36 PM
>>>>> To: Wang Xingchao
>>>>> Cc: alsa-devel@alsa-project.org; Wang, Xingchao
>>>>> Subject: Re: [PATCH 2/2] ALSA: hda - get realtime ELD info when codec
>>>>> suspended
>>>>>
>>>>> At Mon, 24 Jun 2013 07:45:24 -0400,
>>>>> Wang Xingchao wrote:
>>>>>>
>>>>>> when controller/codec in runtime suspended mode, monitor hotplug would
>>>>>> not trigger unsolicited event.
>>
>> And here's the original problem IMO: If you can't detect plug/unplug in
>> runtime suspend mode, the runtime suspend mode is broken. Userspace
>> relies on getting notification when a HDMI/DP connection is
>> plugged/unplugged. If no unsol event is triggered, how is userspace
>> notified?
>
> It can't, so far.  The same thing happens for any other jack
> detections when the power-saving is turned on.
>
> 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?

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 4.5.9.2:
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?


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