Re: [alsa-devel] [PATCH v4 3/3] ALSA: hda: Disabled unused audio controller for Dell platforms with Switchable Graphics

[Kai Heng Feng]

> On Apr 20, 2018, at 8:10 PM, Takashi Iwai <tiwai@xxxxxxx> wrote:
>
> On Fri, 20 Apr 2018 11:44:32 +0200,
> Kai-Heng Feng wrote:
> > Now it's a typical discrete-only system. HDMI audio comes from AMD audio
> > controller, others from Intel audio controller.
> >
> > When SG is enabled, the unused AMD audio contoller still exposes its
> > sysfs, so userspace still opens the control file and stream. If
> > userspace tries to output sound through the stream, it hangs the system.
>
> Hm, could you give more information about how it hangs?

Well, I should say "it hangs the userspace process" instead.

$ speaker-test -t wav -c 2 -D hw:CARD=HDMI,DEV=3
...and it just stopped. Can't Ctrl+C to break it.

> > @@ -1627,6 +1629,42 @@ static void check_msi(struct azx *chip)
> >  	}
> >  }
> >
> > +#if IS_ENABLED(CONFIG_DELL_LAPTOP)
>
> This should be IS_REACHABLE(), as both dell-laptop and HD-audio are
> tristate.

Thanks, will update in next version.

> > +static bool check_dell_switchable_gfx(struct pci_dev *pdev)
>
> I'd remove "_dell" word here.  Such a check would be likely needed for
> other vendors, and it's quite possible that the function will be
> extended to cover a wider DMI table.

Makes sense. Will also update this one.

Kai-Heng

> thanks,
>
> Takashi