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

[Alex Deucher]

On Tue, Oct 7, 2014 at 7:49 PM, Benjamin Herrenschmidt
<benh at kernel.crashing.org> wrote:
> 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 ?
>

Yes, this was definitely fixed on the GPU side.

> 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)

I'm not aware of any such issue, but I can ask the hw guys if there is
anything special required to disable MSIs beyond the pci config space
settings.

Alex

>
> Cheers,
> Ben.
>
>