Re: [PATCH 2/2] ALSA: hda - Bind with i915 only when Intel graphics is present

[Takashi Iwai <tiwai@suse.de>]

On Thu, 31 Mar 2016 14:56:40 +0200,
Ville Syrjälä wrote:
> 
> On Wed, Mar 30, 2016 at 05:46:02PM +0200, Takashi Iwai wrote:
> > On Skylake and onwards, the HD-audio controller driver needs to bind
> > with i915 for having the control of power well audio domain before
> > actually probing the codec.  This leads to the load of i915 driver
> > from the audio driver side.  But, there are systems that have no Intel
> > graphics but Nvidia or AMD GPU, although they still use HD-audio bus
> > for the onboard audio codecs.  On these, loading the i915 driver is
> > nothing but a useless memory and CPU consumption.
> > 
> > A simple way to avoid it is just to look for the Intel graphics PCI
> > entry beforehand, and try to bind with i915 only when such an entry is
> > found.  Currently, it assumes the PCI display class.  If another class
> > appears, this needs to be extended (although it's very unlikely).
> > 
> > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> > ---
> >  sound/hda/hdac_i915.c | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> > 
> > diff --git a/sound/hda/hdac_i915.c b/sound/hda/hdac_i915.c
> > index c62a9f830b84..3c8e6d93d4df 100644
> > --- a/sound/hda/hdac_i915.c
> > +++ b/sound/hda/hdac_i915.c
> > @@ -298,6 +298,17 @@ int snd_hdac_i915_register_notifier(const struct i915_audio_component_audio_ops
> >  }
> >  EXPORT_SYMBOL_GPL(snd_hdac_i915_register_notifier);
> >  
> > +/* check whether intel graphics is present */
> > +static bool i915_gfx_present(void)
> > +{
> > +	static struct pci_device_id ids[] = {
> > +		{ PCI_DEVICE_CLASS(PCI_BASE_CLASS_DISPLAY << 16, 0xff0000) },
> > +		{}
> > +	};
> > +	return pci_dev_present(ids);
> > +}
> 
> Should this be checking for at least the Intel vendor ID? External GPUs
> should be display class devices too, no?

Doh, yes, of course.  This has been slipped while refactoring.


thanks,

Takashi
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