[PATCH v3 4/7] sound/radeon: Add quirk for broken 64-bit MSI

[Benjamin Herrenschmidt]

On Tue, 2014-10-07 at 19:47 -0400, Alex Deucher wrote:
> > While recent ASICs have that problem fixed, they don't seem to
> > be listed in the PCI IDs of the current driver, so let's quirk all
> > the ATI HDMI for now. The consequences are nil on x86 anyway.
> >
> > Signed-off-by: Alex Deucher <alexdeucher at gmail.com>
> > Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> > CC: <stable at vger.kernel.org>
> 
> Further discussion with the hw teams have revealed that this is still
> an issue on newer asics so I think your original patch is correct
> after all.  Just disable 64 bit MSIs on all AMD audio PCI ids.

Ok. You confirm that this is however good on newer video side right ?

Also, is there a known issue that if MSI were once enabled, the chip
still shoots them even if we disable them in config space ?

When testing my new patch set, I was trying to test the error path
when the arch does *not* honor the limitation. The error went back
up to the driver as far as I can tell (ie, pci_enable_msi() failed),
but the system still got into error state as if the card had tried
to shoot an MSI to the wrong address.

(I suspect the graphics side)

Cheers,
Ben.