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Subject[RFC 0/4] dma-fence: Deadline awareness
From: Rob Clark <>

Based on discussion from a previous series[1] to add a "boost" mechanism
when, for example, vblank deadlines are missed. Instead of a boost
callback, this approach adds a way to set a deadline on the fence, by
which the waiter would like to see the fence signalled.

I've not yet had a chance to re-work the drm/msm part of this, but
wanted to send this out as an RFC in case I don't have a chance to
finish the drm/msm part this week.

Original description:

In some cases, like double-buffered rendering, missing vblanks can
trick the GPU into running at a lower frequence, when really we
want to be running at a higher frequency to not miss the vblanks
in the first place.

This is partially inspired by a trick i915 does, but implemented
via dma-fence for a couple of reasons:

1) To continue to be able to use the atomic helpers
2) To support cases where display and gpu are different drivers


Rob Clark (4):
dma-fence: Add deadline awareness
drm/vblank: Add helper to get next vblank time
drm/atomic-helper: Set fence deadline for vblank
drm/scheduler: Add fence deadline support

drivers/dma-buf/dma-fence.c | 39 +++++++++++++++++++++++++
drivers/gpu/drm/drm_atomic_helper.c | 36 +++++++++++++++++++++++
drivers/gpu/drm/drm_vblank.c | 31 ++++++++++++++++++++
drivers/gpu/drm/scheduler/sched_fence.c | 10 +++++++
drivers/gpu/drm/scheduler/sched_main.c | 3 ++
include/drm/drm_vblank.h | 1 +
include/linux/dma-fence.h | 17 +++++++++++
7 files changed, 137 insertions(+)


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