Linux 2.6.39-rc3

Jerome Glisse j.glisse at
Mon Apr 18 08:59:25 PDT 2011

On Mon, Apr 18, 2011 at 11:33 AM, Alex Deucher <alexdeucher at> wrote:
> On Mon, Apr 18, 2011 at 11:29 AM, Jerome Glisse <j.glisse at> wrote:
>> On Mon, Apr 18, 2011 at 11:23 AM, Alex Deucher <alexdeucher at> wrote:
>>> On Sun, Apr 17, 2011 at 10:09 AM, Joerg Roedel <joro at> wrote:
>>>> On Sat, Apr 16, 2011 at 02:54:04PM -0400, Jerome Glisse wrote:
>>>>> If you want to go the printk way you can add printk before each test
>>>>> ring_test, ib_test in r600.c this 2 functions are the own that might
>>>>> trigger the first GPU gart activities.
>>>> Okay, I found the place in source that triggers this. It happens in the
>>>> function r600_ib_test. The interesting thing is that not the ib-command
>>>> itself is responsible but the fence that is emitted afterwards (proved
>>>> by removing the fence command, where the problem went away).
>>>> I don't know enough about the command semantics to make a guess what
>>>> goes wrong there. But maybe you GPU folks have an idea?
>>> I can't think of anything off hand.  It might be worth disabling the
>>> call to r600_ib_test() in r600_init() and then seeing if you get any
>>> errors when the fences are used later on when X starts or just at that
>>> point in the module load sequence.  What's odd is that when you tested
>>> radeon.no_wb=1 you got the same behavior as that disables shadowing of
>>> fence writes to gpu gart mem, so it wouldn't be writing to memory in
>>> that case.
>>> Alex
>> It might be the irq ring write that is faulty.
> That's disabled with no_wb=1 as well.
> Alex

I mean the irq interrupt ring, i don't see this being disabled when no_wb=1


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