broken msi interrupts with radeon rv570 on amd 8151 agp bridge

[Dave Airlie]

On Fri, Nov 6, 2009 at 6:10 AM, Alex Deucher <alexdeucher at gmail.com> wrote:
> 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.
>

Actually I suspect this is different, I'm guessing the PCIE<->AGP bridge
on the radeon card is screwing up the MSI, I suspect we shouldn't enable
MSI on AGP cards ever.

Dave.