broken msi interrupts with radeon rv570 on amd 8151 agp bridge

[Alex Deucher]

On Thu, Nov 5, 2009 at 9:06 AM, Matthew Wilcox <matthew at wil.cx> wrote:
> On Thu, Nov 05, 2009 at 01:57:10PM +0100, Daniel Vetter wrote:
>> When starting a failsafe X session and starting glxgears (which should
>> cause plenty of interrupts to be generated), /proc/interrupts shows
>> absolutely no MSI interrupts arriving. There are no other devices in this
>> box using MSI interrupts.
>>
>> I've also tried with the lastest -linus git tree merged in, with the same
>> effects.
>>
>> Booting with "pci=nomsi" works around the issue. I dunno whether this is a
>> pci or radeon issue therefore I'm posting to both lists. lspci -v (as
>> root) is attached below.
>
> That sucks, and we need to fix it.
>
> It's almost certainly a chipset issue, so my suspicion falls primarily
> on this device:
> 04:01.0 PCI bridge: Advanced Micro Devices [AMD] AMD-8151 AGP Bridge (rev 14) (prog-if 00 [Normal decode])
>
> We have a number of quirks to handle MSIs (both disabling their use, and
> programming the feature in bridges that the BIOS forgot to set up) on
> HyperTransport machines already; could you send both lspci -t and
> lspci -vvvnn (as root) to the linux-pci list?


While working on irq support for newer radeons I've noticed a similar
issue on an rs780 board, but only with the integrated graphics chip
(1002:9610).  MSIs work fine on the PCIE slots and other integrated
peripherals.  When I enable MSIs on the integrated graphics chip, I
get no MSI interrupts arriving for that device.  Other MSI enabled
devices work fine.  I haven't had a chance to test any other rs780
systems with integrated graphics yet.

Alex
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