Re: [PATCH v3 3/3] ALSA: hda: Disabled unused audio controller for Dell platforms with Switchable Graphics

Pali Rohár
2018-04-15T17:17:51Z

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On Saturday 14 April 2018 13:17:11 Lukas Wunner wrote:
> On Sat, Apr 14, 2018 at 12:49:50PM +0200, Pali Rohár wrote:
> > On Saturday 14 April 2018 12:45:12 Lukas Wunner wrote:
> > > On Thu, Apr 12, 2018 at 10:15:41PM +0800, Kai-Heng Feng wrote:
> > > > Do you have any suggestion to check if it connects to the system via
> > > > Thunderbolt?
> > >
> > > Just use pci_is_thunderbolt_attached(), introduced by 8531e283bee6,
> > > like this:
> > >
> > > if (check_dell_switchable_gfx(pci) && !pci_is_thunderbolt_attached(pci))
> >
> > And what about PCI-e device attached to ExpressCard slot?
>
> I don't know of a bullet-proof way to recognize those. In theory
> one could check if the PCIe port above the GPU is a non-hotplug
> root port, but I think there are machines with hotplug capable
> root ports with GPUs below them that aren't actually removable.
>
> However I think ExpressCard-attached GPUs were rare, much less ones
> with integrated HDA controller, so in reality that's probably a
> non-issue.

Hm... maybe another idea: Is it possible to detect which audio pci
device belongs to graphics card via vga_switcheroo? Currently, looking
at output it is same PCI device as graphic card, just different PCI
function.

--
Pali Rohár
pali.rohar@gmail.com

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