From: Rob Clark robdclark@chromium.org
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
[1] https://patchwork.freedesktop.org/series/90331/
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(+)