Re: [PATCH v7 2/8] PCI/VGA: Deal only with VGA class devices

[Sui Jingfeng]

Hi,

On 2023/6/19 11:02, Maciej W. Rozycki wrote:
> On Tue, 13 Jun 2023, Sui Jingfeng wrote:
>
> > Deal only with the VGA devcie(pdev->class == 0x0300), so replace the
>   Typo here: s/devcie/device/.
Thanks a lot,
> > pci_get_subsys() function with pci_get_class(). Filter the non-PCI display
> > device(pdev->class != 0x0300) out. There no need to process the non-display
> > PCI device.
>   I've only come across this patch series now.  Without diving into what
> this code actually does I have just one question as a matter of interest.
>
> > diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
> > index c1bc6c983932..22a505e877dc 100644
> > --- a/drivers/pci/vgaarb.c
> > +++ b/drivers/pci/vgaarb.c
> > @@ -1500,7 +1496,9 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
> >   	struct pci_dev *pdev = to_pci_dev(dev);
> >   	bool notify = false;
> >   
> > -	vgaarb_dbg(dev, "%s\n", __func__);
> > +	/* Only deal with VGA class devices */
> > +	if (pdev->class != PCI_CLASS_DISPLAY_VGA << 8)
> > +		return 0;
>   Hmm, shouldn't this also handle PCI_CLASS_NOT_DEFINED_VGA?

If your machine have only one such a VGA card, it probably don't hurt.

But, such a card will also get ignored originally (before applying this 
patch).

>   As far as I
> know it is the equivalent of PCI_CLASS_DISPLAY_VGA for PCI <= 2.0 devices
> that were implemented before the idea of PCI device classes has developed
> into its current form.

If multiple video card problems on your machine is matter,

then I think it do deserve another patch to clarify this issue and to 
explain the rationale.

>   I may have such a VGA device somewhere.
>
>    Maciej