[PATCH] agp/amd64: Bind to unsupported devices only if AGP is present

[Ben Hutchings]

On Sat, 2025-06-21 at 14:29 +0200, Lukas Wunner wrote:
> On Sat, Jun 21, 2025 at 02:07:40PM +0200, Ben Hutchings wrote:
> > On Sat, 2025-06-21 at 11:40 +0200, Lukas Wunner wrote:
> > > Since commit 172efbb40333 ("AGP: Try unsupported AGP chipsets on x86-64 by
> > > default"), the AGP driver for AMD Opteron/Athlon64 CPUs attempts to bind
> > > to any PCI device.
> > > 
> > > On modern CPUs exposing an AMD IOMMU, this results in a message with
> > > KERN_CRIT severity:
> > > 
> > >   pci 0000:00:00.2: Resources present before probing
> > > 
> > > The driver used to bind only to devices exposing the AGP Capability, but
> > > that restriction was removed by commit 6fd024893911 ("amd64-agp: Probe
> > > unknown AGP devices the right way").
> > 
> > That didn't remove any restriction as the probe function still started
> > by checking for an AGP capability.  The change I made was that the
> > driver would actually bind to devices with the AGP capability instead of
> > starting to use them without binding.
> 
> The message above would not be emitted without your change.
> 
> The check for the AGP capability in agp_amd64_probe() is too late
> to prevent the message.  That's because the message is emitted
> before ->probe() is even called.

I understand that.  But I don't feel that the explanation above
accurately described the history here.

Ben.

-- 
Ben Hutchings
All the simple programs have been written, and all the good names taken
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