Am 28.10.2016 um 19:37 schrieb Mario Kleiner:
On 10/28/2016 03:34 AM, Michel Dänzer wrote:
On 27/10/16 10:33 PM, Mike Lothian wrote:
Just another gentle ping to see where you are with this?
I haven't got a chance to look into this any further.
Fwiw., as a proof of concept, the attached experimental patch does
work as tested on Intel HD Haswell + AMD R9 380 Tonga under amdgpu and
DRI3/Present when applied to drm-next (updated from a few days ago).
With DRI_PRIME=1 tearing for page-flipped fullscreen windows is gone
under all loads. The tearing with "windowed" windows now looks as
expected for regular tearing not related to Prime.
Yeah, that's pretty much what I had in mind as well. You additionally
need to wait for the shared fences when you export the BO for the first
time, but that's only a nitpick.
ftrace confirms the i915 driver's pageflip function is waiting on the
fence in reservation_object_wait_timeout_rcu() as it should.
That entry->tv.shared needs to be set false for such buffers in
amdgpu_bo_list_set() makes sense to me, as that is part of the buffer
validation for command stream submission. There are other places in
the driver where tv.shared is set, which i didn't check so far.
I don't know which of these would need to be updated with a "exported
bo" check as well, e.g., for video decoding or maybe gpu compute?
Adding or removing the check to amdgpu_gem_va_update_vm(), e.g., made
no difference. I assume that makes sense because that functions seems
to deal with amdgpu internal vm page tables or page table entries for
such a bo, not with something visible to external clients?
Yes, exactly. VM updates doesn't matter for anybody else than amdgpu.
Additional to that we don't even add a fence to the shared slot we
reserve (could probably drop that for optimization).
Please remove the debugging stuff and the extra code on the VM updates
and add a reservation_object_wait_timeout_rcu() to the export path and
we should be good to go.
Regards,
Christian.
All i can say is it fixes 3D rendering under DRI3 + Prime +
pageflipping without causing any obvious new problems.
-mario
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