On Tue, Jul 27, 2021 at 3:44 AM Michel Dänzer michel@daenzer.net wrote:
On 2021-07-27 1:38 a.m., Rob Clark wrote:
From: Rob Clark robdclark@chromium.org
For an atomic commit updating a single CRTC (ie. a pageflip) calculate the next vblank time, and inform the fence(s) of that deadline.
Signed-off-by: Rob Clark robdclark@chromium.org
drivers/gpu/drm/drm_atomic_helper.c | 36 +++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index bc3487964fb5..f81b20775b15 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1406,6 +1406,40 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev, } EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_enables);
+/*
- For atomic updates which touch just a single CRTC, calculate the time of the
- next vblank, and inform all the fences of the of the deadline.
- */
+static void set_fence_deadline(struct drm_device *dev,
struct drm_atomic_state *state)+{
struct drm_crtc *crtc, *wait_crtc = NULL;struct drm_crtc_state *new_crtc_state;struct drm_plane *plane;struct drm_plane_state *new_plane_state;ktime_t vbltime;int i;for_each_new_crtc_in_state (state, crtc, new_crtc_state, i) {if (!wait_crtc)return;Either this return or the next one below would always be taken, I doubt this was intended.
oops, the condition here is mistakenly inverted, it was meant to bail if there is more than a single CRTC
wait_crtc = crtc;}/* If no CRTCs updated, then nothing to do: */if (!wait_crtc)return;if (drm_crtc_next_vblank_time(wait_crtc, &vbltime))return;for_each_new_plane_in_state (state, plane, new_plane_state, i) {if (!new_plane_state->fence)continue;dma_fence_set_deadline(new_plane_state->fence, vbltime);}vblank timestamps correspond to the end of vertical blank, the deadline should be the start of vertical blank though.
hmm, I suppose this depends on whether the hw actually has separate irq's for frame-done and vblank (and whether the driver differentiates).. and if the display controller is doing some buffering, the point at which it wants to flip could be a bit earlier still. Maybe we just want a kms driver provided offset for how early it wants the deadline relative to vblank?
BR, -R
-- Earthling Michel Dänzer | https://redhat.com Libre software enthusiast | Mesa and X developer