Re: [PATCH] drm/amdgpu: add the accelerator pcie class

[Christoph Hellwig <hch@infradead.org>]

On Tue, May 23, 2023 at 10:02:32AM -0400, Alex Deucher wrote:
> On Tue, May 23, 2023 at 5:25 AM Christoph Hellwig <hch@infradead.org> wrote:
> >
> > On Tue, May 23, 2023 at 12:02:32PM +0800, Shiwu Zhang wrote:
> > > +     { PCI_DEVICE(0x1002, PCI_ANY_ID),
> > > +       .class = PCI_CLASS_ACCELERATOR_PROCESSING << 8,
> > > +       .class_mask = 0xffffff,
> > > +       .driver_data = CHIP_IP_DISCOVERY },
> >
> > Probing for every single device of a given class for a single vendor
> > to a driver is just fundamentaly wrong.  Please list the actual IDs
> > that the driver can handle.
> 
> How so?  The driver handles all devices of that class.  We already do
> that for PCI_CLASS_DISPLAY_VGA and PCI_CLASS_DISPLAY_OTHER.  Other
> drivers do similar things.

How is that going to work in the long run?  The chances of totally
incompatbile devices from the same vendor appearing is absolutely given.

> The hda audio driver does the same thing
> for PCI_CLASS_MULTIMEDIA_HD_AUDIO for example.
>

That, just like PCI_CLASS_STORAGE_EXPRESS is a different case, as
the class is associated with an actual documented programming interface.