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

[Takashi Iwai]

At Tue, 25 Jun 2013 09:45:04 +0200,
David Henningsson wrote:
> 
> 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 at suse.de]
> >>>>> Sent: Monday, June 24, 2013 7:36 PM
> >>>>> To: Wang Xingchao
> >>>>> Cc: alsa-devel at 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?

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 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?

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.


Takashi