From: Rob Clark <[email protected]>
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 <[email protected]>
---
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;
+ 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);
+ }
+}
+
/**
* drm_atomic_helper_wait_for_fences - wait for fences stashed in plane state
* @dev: DRM device
@@ -1435,6 +1469,8 @@ int drm_atomic_helper_wait_for_fences(struct drm_device *dev,
struct drm_plane_state *new_plane_state;
int i, ret;
+ set_fence_deadline(dev, state);
+
for_each_new_plane_in_state(state, plane, new_plane_state, i) {
if (!new_plane_state->fence)
continue;
--
2.31.1
On 2021-07-27 1:38 a.m., Rob Clark wrote:
> From: Rob Clark <[email protected]>
>
> 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 <[email protected]>
> ---
> 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.
> + 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.
--
Earthling Michel Dänzer | https://redhat.com
Libre software enthusiast | Mesa and X developer
On Tue, Jul 27, 2021 at 3:44 AM Michel Dänzer <[email protected]> wrote:
>
> On 2021-07-27 1:38 a.m., Rob Clark wrote:
> > From: Rob Clark <[email protected]>
> >
> > 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 <[email protected]>
> > ---
> > 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