Messages in this thread | | | Date | Thu, 9 Aug 2012 12:34:30 +0200 | From | Thierry Reding <> | Subject | Re: [PATCH] ALSA: hda - Defer probe when loading patch firmware |
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On Thu, Aug 09, 2012 at 10:21:15AM +0200, Takashi Iwai wrote: > At Thu, 9 Aug 2012 10:07:13 +0200, > Thierry Reding wrote: > > > > On Thu, Aug 09, 2012 at 09:42:48AM +0200, Takashi Iwai wrote: > > > At Thu, 9 Aug 2012 09:36:42 +0200, > > > Thierry Reding wrote: > > > > > > > > On Thu, Aug 09, 2012 at 09:31:30AM +0200, Takashi Iwai wrote: > > > > > At Thu, 9 Aug 2012 09:08:13 +0200, > > > > > Thierry Reding wrote: > > > > > > > > > > > > On Thu, Aug 09, 2012 at 08:57:13AM +0200, Takashi Iwai wrote: > > > > > > > At Thu, 9 Aug 2012 08:45:23 +0200, > > > > > > > Thierry Reding wrote: > > > > > > > > > > > > > > > > Recent changes to the firmware loading helpers cause drivers to stall > > > > > > > > when firmware is loaded during the module_init() call. The snd-hda-intel > > > > > > > > module requests firmware if the patch= parameter is used to load a patch > > > > > > > > file. This patch works around the problem by deferring the probe in such > > > > > > > > cases, which will cause the module to load successfully and the driver > > > > > > > > binding to the device outside the module_init() call. > > > > > > > > > > > > > > Is the "recent" change meant 3.6 kernel, or in linux-next? > > > > > > > > > > > > > > In anyway, I don't understand why such a change was allowed. Most > > > > > > > drivers do call request_firmware() at the device probing time. > > > > > > > If this really has to be resolved in the driver side, it must be a bug > > > > > > > in the firmware loader core code. > > > > > > > > > > > > A good explanation of the problem and subsequent discussion can be found > > > > > > here: > > > > > > > > > > > > http://article.gmane.org/gmane.linux.drivers.video-input-infrastructure/49975 > > > > > > > > > > Yeah, but it doesn't justify this ugly module option. > > > > > It's a simple bug. Papering over it with this option doesn't fix > > > > > anything. > > > > > > > > It's not an option, all it does is defer probing if and only if the > > > > patch parameter was specified to make sure the firmware load won't > > > > stall. I realize that this may not be an optimal solution, but at least > > > > it fixes the problem with no fallout. > > > > > > Ah sorry, I misread the patch. > > > > > > Then it shouldn't be checked at that point. Since 3.5 kernel, the > > > probing code was already split for vga_switcheroo support. > > > > Yes, I saw that. But unless you actually use vga_switcheroo, the second > > stage, azx_probe_continue(), will still be called from azx_probe() and > > therefore ultimately from module_init(). > > Yeah, but this could be easily delayed. The split was already done, > so the next step would be to return after the first half at probe, > then call the second half later. > > > Before coming up with this patch I actually did play around a bit with > > using the asynchronous firmware load functions but it turned out to be > > rather difficult to do so I opted for the easy way. The biggest problem > > I faced was that since patch loading needs to be done very early on, a > > lot of the initialization would need to be done after .probe() and many > > things could still fail, so cleaning up after errors would become > > increasingly difficult. > > async probe is also on my TODO list, but it's deferred ;) > > > > The point you added is the second stage. > > > > I don't understand this sentence. > > I meant that your patch added the check at the second-half probing > function (azx_probe_contine()). That is, it could be already the > point triggered by vga_switcheroo handler, not via module_init any > longer. > > So, after rethinking what you suggested, I wrote a quick patch below. > Could you check whether this works?
It oopses, though I can't quite tell where. I need to test some more later to see where it goes wrong.
Thierry
> > > Takashi > > --- > diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c > index c8aced1..4e5839a 100644 > --- a/sound/pci/hda/hda_intel.c > +++ b/sound/pci/hda/hda_intel.c > @@ -559,13 +559,17 @@ enum { > * VGA-switcher support > */ > #ifdef SUPPORT_VGA_SWITCHEROO > +#define use_vga_switcheroo(chip) ((chip)->use_vga_switcheroo) > +#else > +#define use_vga_switcheroo(chip) 0 > +#endif > + > +#if defined(SUPPORT_VGA_SWITCHEROO) || defined(CONFIG_SND_HDA_PATCH_LOADER) > #define DELAYED_INIT_MARK > #define DELAYED_INITDATA_MARK > -#define use_vga_switcheroo(chip) ((chip)->use_vga_switcheroo) > #else > #define DELAYED_INIT_MARK __devinit > #define DELAYED_INITDATA_MARK __devinitdata > -#define use_vga_switcheroo(chip) 0 > #endif > > static char *driver_short_names[] DELAYED_INITDATA_MARK = { > @@ -3154,6 +3158,20 @@ static int __devinit azx_probe(struct pci_dev *pci, > struct azx *chip; > int err; > > +#ifdef CONFIG_SND_HDA_PATCH_LOADER > + /* delayed probe */ > + card = pci_get_drvdata(pci); > + if (card) { > + struct azx *chip = card->private_data; > + if (chip->disabled) > + return 0; /* will be loaded via vga_switcheroo */ > + err = azx_probe_continue(chip); > + if (err < 0) > + goto out_free; > + return 0; > + } > +#endif > + > if (dev >= SNDRV_CARDS) > return -ENODEV; > if (!enable[dev]) { > @@ -3175,19 +3193,28 @@ static int __devinit azx_probe(struct pci_dev *pci, > goto out_free; > card->private_data = chip; > > +#ifndef CONFIG_SND_HDA_PATCH_LOADER > + /* continue probing if no patch loader is required */ > if (!chip->disabled) { > err = azx_probe_continue(chip); > if (err < 0) > goto out_free; > } > +#endif > > pci_set_drvdata(pci, card); > > dev++; > + > +#ifdef CONFIG_SND_HDA_PATCH_LOADER > + return -EPROBE_DEFER; /* continue probing later for request_firmware() */ > +#else > return 0; > +#endif > > out_free: > snd_card_free(card); > + pci_set_drvdata(pci, NULL); > return err; > } > > > [unhandled content-type:application/pgp-signature] | |