[Intel-gfx] [PATCH] drm/i915: flush system agent TLBs on SNB so we can WC map the PTEs

[Dave Airlie]

On Thu, Oct 11, 2012 at 7:54 PM, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> On Thu, 11 Oct 2012 20:29:47 -0300
> Paulo Zanoni <przanoni at gmail.com> wrote:
>
>> Hi
>>
>> 2012/10/11 Jesse Barnes <jbarnes at virtuousgeek.org>:
>> > I've only lightly tested this so far, but the corruption seems to be
>> > gone if I write the GFX_FLSH_CNTL reg after binding an object.  This
>> > register should control the TLB for the system agent, which is what CPU
>> > mapped objects will go through.
>> >
>> > Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
>>
>> I'm not sure if this is the patch you asked me to test on IRC, but,
>> well this is the patch I tested :)
>>
>> I tested it on HSW on top of dinq + some other patches. Booted the
>> machine, ran mostly xfterm4 under Xfce, but I also ran firefox,
>> gnome-shell and restarted X a few times. No GPU hangs so far. I'm
>> testing this for about 3-4 hours.
>>
>> I do have to say that I could not find this register on the HSW
>> documentation, but I also did no see any "Unclaimed write" messages
>> containing the 101008 address... I'm a little confused.
>>
>> And the interesting thing: intel_gpu_tools is useless now. I keep
>> getting "Couldn't map MMIO region: Resource temporarily unavailable".
>> Do you see this too?
>
> No I haven't seen that, I ran some tests today with the tip of the tree
> too...  Dunno why the resource files would return EBUSY?  Maybe because
> a driver is bound?

More likely because of some WB/WC/UC collision. We don't like aliases.

Dave.