Re: [Xen-devel] [Qemu-devel] [RFC][PATCH 2/2] xen:i386:pc_piix: create isa bridge specific to IGD passthrough

["Chen, Tiejun" <tiejun.chen@xxxxxxxxx>]

On 2014/11/17 17:25, Michael S. Tsirkin wrote:
> On Mon, Nov 17, 2014 at 04:48:32PM +0800, Chen, Tiejun wrote:
> > On 2014/11/17 14:10, Michael S. Tsirkin wrote:
> > > On Mon, Nov 17, 2014 at 10:47:56AM +0800, Chen, Tiejun wrote:
> > > > On 2014/11/5 22:09, Michael S. Tsirkin wrote:
> > > > > On Wed, Nov 05, 2014 at 03:22:59PM +0800, Tiejun Chen wrote:
> > > > > > Currently IGD drivers always need to access PCH by 1f.0, and
> > > > > > PCH vendor/device id is used to identify the card.
> > > > > >
> > > > > > Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
> > > > > > ---
[snip]

> Cleaner:
>          if (!pci_dev) {
>                 fprintf
>                 return;
>         }
>           pci_config_set_device_id(pci_dev->config, pch_id);
I will address all comments and thanks.

> > +    }
> > +}
> > +
> >   /* init */
> >
> >   static int xen_pt_initfn(PCIDevice *d)
> > @@ -682,6 +770,9 @@ static int xen_pt_initfn(PCIDevice *d)
> >           return -1;
> >       }
> >
> > +    /* Register ISA bridge for passthrough GFX. */
> > +    xen_igd_passthrough_isa_bridge_create(s, &s->real_device);
> > +
> >       /* reinitialize each config register to be emulated */
> >       if (xen_pt_config_init(s)) {
> >           XEN_PT_ERR(d, "PCI Config space initialisation failed.\n");
> >
> > Note I will introduce a inline function in another patch,
> >
> > +static inline int is_vga_passthrough(XenHostPCIDevice *dev)
> > +{
> > +    return (xen_has_gfx_passthru && (dev->vendor_id == PCI_VENDOR_ID_INTEL)
> > +            && ((dev->class_code >> 0x8) == PCI_CLASS_DISPLAY_VGA));
> > +}
> >
> > Thanks
> > Tiejun
> Why bother with all these conditions?
> Won't it be enough to check dev->vendor_id == PCI_VENDOR_ID_INTEL?
If this is just used for IGD, its always fine without checking vendor_id.

So after remove that check, I guess I need to rename that as 
is_igd_vga_passthrough() to make sense.
Thanks
Tiejun

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