At Mon, 3 Dec 2012 22:25:52 +0800,
Daniel J Blueman wrote:
>
> On 3 December 2012 19:17, Takashi Iwai <ti...@suse.de> wrote:
> > At Wed, 28 Nov 2012 09:45:39 +0100,
> > Takashi Iwai wrote:
> >>
> >> At Wed, 28 Nov 2012 11:45:07 +0800,
> >> Daniel J Blueman wrote:
> >> >
> >> > Hi Seth, Dave, Takashi,
> >> >
> >> > If I power down the unused discrete GPU before lightdm starts by
> >> > fiddling with the sysfs file [1] in the upstart script, I see a race
> >> > manifesting as the discrete GPU's HDA controller timing out to
> >> > commands [2].
> >> >
> >> > Adding some debug, I see that the registered audio devices are put
> >> > into D3 before the GPU is, but it turns out that the discrete (and
> >> > internal) GPU's HDA controller gets registered a bit later, so the
> >> > list is empty. The symptom is since the HDA driver it's talking to
> >> > hardware which is now in D3.
> >> >
> >> > We could add a mutex to nouveau to allow us to wait for the DGPU HDA
> >> > controller, but perhaps this should be solved at a higher level in the
> >> > vgaswitcheroo code; what do you think?
> >>
> >> Maybe it's a side effect for the recent effort to fix another race in
> >> the probe. A part of them problem is that the registration is done at
> >> the very last of probing.
> >>
> >> Instead of delaying the registration, how about the patch below?
> >
> > Ping. If this really works, I'd like to queue it for 3.8 merge, at
> > least...
>
> Ping ack; I was trying to find time to understand another race that
> occurs with GPU probing after switching, but is separate from the
> situation before switching, here.
>
> In the context of writing the switch, it looks like struct azx isn't
> allocated by the time azx_vs_set_state accesses it [1,2]; racing with
> azx_codec_create?
It was allocated, but it wasn't assigned properly in pci drvdata.
Below is the revised patch. Just moved pci_set_drvdata() before
register_vga_switcheroo(). Could you retest with it?
thanks,
Takashi
---
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 4bb52da..b7c482a 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -49,6 +49,7 @@
#include <linux/pm_runtime.h>
#include <linux/clocksource.h>
#include <linux/time.h>
+#include <linux/completion.h>
#ifdef CONFIG_X86
/* for snoop control */
@@ -469,6 +470,7 @@ struct azx {
/* locks */
spinlock_t reg_lock;
struct mutex open_mutex;
+ struct completion probe_wait;
/* streams (x num_streams) */
struct azx_dev *azx_dev;
@@ -2790,6 +2792,7 @@ static bool azx_vs_can_switch(struct pci_dev *pci)
struct snd_card *card = pci_get_drvdata(pci);
struct azx *chip = card->private_data;
+ wait_for_completion(&chip->probe_wait);
if (chip->init_failed)
return false;
if (chip->disabled || !chip->bus)
@@ -2851,6 +2854,9 @@ static int azx_free(struct azx *chip)
azx_notifier_unregister(chip);
+ chip->init_failed = 1; /* to be sure */
+ complete(&chip->probe_wait);
+
if (use_vga_switcheroo(chip)) {
if (chip->disabled && chip->bus)
snd_hda_unlock_devices(chip->bus);
@@ -3156,6 +3162,7 @@ static int __devinit azx_create(struct snd_card *card,
struct pci_dev *pci,
INIT_LIST_HEAD(&chip->pcm_list);
INIT_LIST_HEAD(&chip->list);
init_vga_switcheroo(chip);
+ init_completion(&chip->probe_wait);
chip->position_fix[0] = chip->position_fix[1] =
check_position_fix(chip, position_fix[dev]);
@@ -3462,17 +3469,8 @@ static int __devinit azx_probe(struct pci_dev *pci,
}
#endif /* CONFIG_SND_HDA_PATCH_LOADER */
- if (probe_now) {
- err = azx_probe_continue(chip);
- if (err < 0)
- goto out_free;
- }
-
pci_set_drvdata(pci, card);
- if (pci_dev_run_wake(pci))
- pm_runtime_put_noidle(&pci->dev);
-
err = register_vga_switcheroo(chip);
if (err < 0) {
snd_printk(KERN_ERR SFX
@@ -3480,11 +3478,22 @@ static int __devinit azx_probe(struct pci_dev *pci,
goto out_free;
}
+ if (probe_now) {
+ err = azx_probe_continue(chip);
+ if (err < 0)
+ goto out_free;
+ }
+
+ if (pci_dev_run_wake(pci))
+ pm_runtime_put_noidle(&pci->dev);
+
dev++;
+ complete(&chip->probe_wait);
return 0;
out_free:
snd_card_free(card);
+ pci_set_drvdata(pci, NULL);
return err;
}
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