[alsa-devel] [3.6-rc7] switcheroo race with Intel HDA...
tiwai at suse.de
Tue Oct 9 12:07:21 CEST 2012
At Tue, 09 Oct 2012 12:04:08 +0200,
Takashi Iwai wrote:
> At Tue, 9 Oct 2012 00:34:09 +0800,
> Daniel J Blueman wrote:
> > On 8 October 2012 20:58, Takashi Iwai <tiwai at suse.de> wrote:
> > > At Tue, 25 Sep 2012 13:20:05 +0800,
> > > Daniel J Blueman wrote:
> > >> On my Macbook with a discrete Nvidia GPU, there is a race between
> > >> selecting the integrated GPU and putting the discrete GPU into D3 ,
> > >> reliably causing a kernel oops .
> > >>
> > >> Introducing a delay of ~1s between the calls prevents this. When the
> > >> second 'OFF' write path executes, it looks like struct azx at
> > >> card->private_data hasn't yet been allocated yet , so there is
> > >> likely some locking missing.
> > >
> > > It's rather pci_get_drvdata() returning NULL (i.e. card is NULL, thus
> > > card->private_data causes Oops). Could you check the patch like below
> > > and see whether you get a kernel warning (but no Oops) or the problem
> > > gets fixed by shifting the assignment of pci drvdata?
> > [...]
> > Good patching. Calling pci_set_drvdata later prevents the oops in HDA,
> > though we see unexpected 0x0 responses in the response ring buffer
> > , which we don't see when there's a >~1.5s delay between IGD and
> > OFF.
> If the previous patch fixed, it means that the switching occurred
> during the device was being probed. Maybe a better approach to
> register the VGA switcheroo after the proper initialization.
> The patch below is a revised one. Please give it a try.
Also, it's not clear which card spews the spurious response.
Apply the patch below in addition.
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index f09ff6c..9a0a29d 100644
@@ -829,8 +829,9 @@ static void azx_update_rirb(struct azx *chip)
- snd_printk(KERN_ERR SFX "spurious response %#x:%#x, "
+ snd_printk(KERN_ERR SFX "%s: spurious response %#x:%#x, "
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