[Intel-gfx] [patch] PCI ID review

[Rodrigo Vivi]

On Mon, Apr 27, 2020 at 11:18:46AM -0400, Alexei Podtelezhnikov wrote:
> On Mon, Apr 27, 2020 at 10:45 AM Chris Wilson <chris at chris-wilson.co.uk> wrote:
> >
> > Quoting Alexei Podtelezhnikov (2020-04-27 15:40:42)
> > > >
> > > > These do not exist. They are fake PCI-ID for Windows95 multi monitor.
> > > > The single device appears twice on the bus as a second function. We
> > > > never had that restriction and could do multiple monitors on the single
> > > > device.
> > >
> > > Windows 10 drivers list them, they do show up on lspci and I'll quote
> > > from Atom datasheet.
> > > "This register is unique in Function 1 (the Function 0 DID is
> > > separate). This difference in Device ID is necessary for allowing
> > > distinct Plug and Play enumeration of function 1 when both function 0
> > > and function 1 have the same class code."
> > > Whatever this means.
> >
> > It means it's a hack for the Window's driver. There is no HW behind it.
> 
> Intel talks about two separate engines (threads?)
> https://www.intel.com/content/www/us/en/support/articles/000005880/graphics-drivers/legacy-graphics.html
> https://www.intel.com/content/www/us/en/support/articles/000005747/graphics-drivers.html
> Still not buying?

Hi Alexei, thanks for these.

With this information in mind it looks very wrong to simply add the PCI ID.

ADD2 device is not supported by i915. I don't believe it will be as simple
as just adding the PCI ID here.

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