[alsa-devel] [PATCH] ALSA: hda - Disable runtime PM on LynxPoint(-LP) controllers

[Takashi Iwai]

At Wed, 20 Nov 2013 13:05:23 +0100,
Takashi Iwai wrote:
> 
> At Wed, 20 Nov 2013 09:54:42 +0100,
> David Henningsson wrote:
> > 
> > (Adding Mengdong to cc)
> > 
> > On 11/19/2013 05:51 PM, Takashi Iwai wrote:
> > > We got bug reports of the stalled HD-audio, typically after S3 or S4,
> > > and it turned out that they seemed triggered by runtime PM on Lynx
> > > Point and Lynx Point-LP controllers.  As there is no way to recover
> > > properly from the stalled controller, it's safer to disable the
> > > runtime PM support on these chips for now.
> > 
> > Oh, this is a bit sad news. Have you talked to Intel about it?
> > 
> > Anyway, I saw something similar a while ago, but never with access to
> > the hardware, and then it was difficult to reproduce for the person on
> > the other side. Nevertheless, when I read through the PM code I found
> > that the GCTL register was sometimes accessed with readb (although it is
> > a 32 bit register), so I wrote a patch for that, but the testing results
> > of this patch were a bit inconclusive, so I never upstreamed it.
> > 
> > Anyway, I'm attaching the draft patch. Do you think it could be related?
> 
> It didn't change the behavior although the change looks good.
> 
> After a long debugging session in this morning, I finally nailed
> down.  This was the fault in the sound driver after all, shamefully :)
> 
> The fix patch is below.
> 
> The code needs a bit clean up, and I have it, but will apply this for
> 3.14.
> 
> 
> Takashi
> 
> ===
> 
> From: Takashi Iwai <tiwai at suse.de>
> Subject: [PATCH 1/2] ALSA: hda - Fix unbalanced runtime PM notification at
>  resume

BTW, it's marked as 1/2 just because of the clean up patch I mentioned
above.  Only this one is needed for now.


Takashi