[alsa-devel] [PATCH] ALSA: hda - delay resume haswell hdmi codec in system resume

[Takashi Iwai]

At Mon, 08 Apr 2013 14:20:28 +0200,
David Henningsson wrote:
> 
> On 04/08/2013 01:59 PM, Takashi Iwai wrote:
> > At Mon, 08 Apr 2013 13:35:25 +0200,
> > David Henningsson wrote:
> >>
> >> On 04/08/2013 01:06 PM, Lin, Mengdong wrote:
> >>>> -----Original Message-----
> >>>> From: Takashi Iwai [mailto:tiwai at suse.de]
> >>>> Sent: Monday, April 08, 2013 6:24 PM
> >>>> To: David Henningsson
> >>>> Cc: Lin, Mengdong; alsa-devel at alsa-project.org
> >>>> Subject: Re: [alsa-devel] [PATCH] ALSA: hda - delay resume haswell hdmi codec
> >>>> in system resume
> >>>>
> >>>> At Mon, 08 Apr 2013 11:49:09 +0200,
> >>>> David Henningsson wrote:
> >>>>>
> >>>>> I'm still not understanding this patch.
> >>>>>
> >>>>> We of course cannot have a situation where HDMI jack detection is not
> >>>>> correctly working after S3, which looks like would be the case here?
> >>>>
> >>>> No.  The patch itself has nothing to do with the HDMI jack detection at all.
> >>>> This intrinsic unsol event is (according to Intel) guaranteed to be issued once at
> >>>> the audio codec initialization, at least for Haswell.
> >>
> >> Well, if no process is using the HDMI codec actively, nothing will
> >> initialize the resume, and the HDMI codec will not initialized at all, i
> >> e, no unsol events enabled in the first place?
> >
> > No, the intrinsic unsol event that is issued for this seems irrelevant
> > from the jack state (i.e. active usage).
> >
> >> (The counter argument would be; if nobody uses HDMI codec, does it
> >> matter that it is not initialized, but I'm unsure if e g "amixer
> >> contents" or listeners on legacy /dev/input actually powers up the chip.)
> >
> > The problem is that the codec resume is always performed no matter
> > whether the device is used or not.  This was different in the past but
> > it's been changed in that way because there are cases where you need
> > to initialize the hardware properly once (e.g. mute-LED toggling).
> >
> >
> >>>>> Second, I just saw on a machine we're working on, the symptoms: one of
> >>>>> the pins in D3 and the right channel muted. And this was on a clean
> >>>>> boot, not after S3 suspend/resume cycle.
> >>>>
> >>>> Maybe another problem.  Maybe not.  Does the problem persist if you reload
> >>>> the driver (without invocation of alsactl via udev)?
> >>>
> >>> Hi Takashi and David,
> >>>
> >>> This is the same dependency issue as after system suspend/resume cycles, with same phenomenon.
> >>> I duplicated this error if I boot without an HDMI/DP cable connected and connect the cable later.
> >>> Maybe we need to delay codec operations on initialization like in resume case.
> >>
> >> So it's a problem both on hotplug and S3...
> >
> > In the case of hotplug, you don't hit the inconsistent power sate
> > we're trying to solve.  The graphics has been already powered up.
> >
> >
> >>>>> To look at the problem again: If the problem is that something must be
> >>>>> done on the graphics driver side first and then on the audio side,
> >>>>> wouldn't the solution be for the video driver and audio driver to
> >>>>> communicate somehow?
> >>>>
> >>>> Yes, the pm domain support is necessary sooner or later, as I already discussed
> >>>> shortly with Dave Airlie.  However...
> >>>
> >>> Liam will propose Gfx driver team to implement a pm domain.
> >>>
> >>>>> And resume (and possibly init?) would not complete until first the
> >>>>> graphics driver has done its resume, and after that, the audio driver.
> >>>>> I e, userspace will remain frozen until both drivers have completed a
> >>>>> correct resume.
> >>>>
> >>>> ... the resume problem can't be fixed only by the usual pm domain serialization.
> >>>> The graphics initialization for the audio bit is done asynchronously, thus we
> >>>> can't guarantee the audio codec is really ready after the graphics driver returns
> >>>> from the resume callback.
> >>>> It shows as if it's ready (you can turn it to D0) but actually it doesn't change on
> >>>> the hardware.  Thus, the serialization with an unsol event wait seems
> >>>> mandatory for the time being.
> >>>>
> >>> It seems so. We have not found better solution now :-(
> >>> I've revised the patch for system suspend/resume case. Please review.
> >>
> >> If this problem can be detected by looking at the pin and finding that
> >> it is in D3,
> >
> > No, you can't see that it's D3.  The controller chip _shows_ it's in
> > D0 while it's actually in D3.  That's the problem.
> >
> > So, this is actually a hardware design bug.  But we need to live with
> > that.
> 
> Then I'm not sure it's the same problem; because for me I can see the D3 
> in the codec proc output.

I suppose you didn't set the powersave for it, right?

BTW, the main problem was about the FG node, which you can't judge
from the proc output, unfortunately.


Takashi