On Sun, Aug 02, 2020 at 02:14:06PM -0500, Bjorn Helgaas wrote:
> Wait, I'm not convinced yet. I know that if a PCI read fails, you
> normally get ~0 data because the host bridge fabricates it to complete
> the CPU load.
>
> But what guarantees that a PCI config register cannot contain ~0?
Well, I don't think you can differentiate that case, right?
I guess this is where the driver knowledge comes into play: if the read
returns ~0, the pci_read_config* should probably return in that case
something like:
PCIBIOS_READ_MAYBE_FAILED
to denote it is all 1s and then the caller should be able to determine,
based on any of domain:bus:slot.func and whatever else the driver knows
about its hardware, whether the 1s are a valid value or an error.
Hopefully.
Or something better of which I cannot think of right now...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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