The general approach seems to make sense now I think.
One minor thing which I'm missing is adding support for this to the dma_fence_array and dma_fence_chain containers.
Regards, Christian.
Am 07.08.21 um 20:37 schrieb Rob Clark:
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:
- To continue to be able to use the atomic helpers
- To support cases where display and gpu are different drivers
[1] https://patchwork.freedesktop.org/series/90331/
v1: https://patchwork.freedesktop.org/series/93035/ v2: Move filtering out of later deadlines to fence implementation to avoid increasing the size of dma_fence
Rob Clark (5): 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 drm/msm: Add deadline based boost support
drivers/dma-buf/dma-fence.c | 20 +++++++ drivers/gpu/drm/drm_atomic_helper.c | 36 ++++++++++++ drivers/gpu/drm/drm_vblank.c | 31 ++++++++++ drivers/gpu/drm/msm/msm_fence.c | 76 +++++++++++++++++++++++++ drivers/gpu/drm/msm/msm_fence.h | 20 +++++++ drivers/gpu/drm/msm/msm_gpu.h | 1 + drivers/gpu/drm/msm/msm_gpu_devfreq.c | 20 +++++++ drivers/gpu/drm/scheduler/sched_fence.c | 25 ++++++++ drivers/gpu/drm/scheduler/sched_main.c | 3 + include/drm/drm_vblank.h | 1 + include/drm/gpu_scheduler.h | 6 ++ include/linux/dma-fence.h | 16 ++++++ 12 files changed, 255 insertions(+)