From: Rob Clark <robdclark@chromium.org>
To: "Michel Dänzer" <michel@daenzer.net>
Cc: "Rob Clark" <robdclark@gmail.com>,
"Matthew Brost" <matthew.brost@intel.com>,
"Thomas Zimmermann" <tzimmermann@suse.de>,
"David Airlie" <airlied@linux.ie>,
"Christian König" <ckoenig.leichtzumerken@gmail.com>,
"open list" <linux-kernel@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>
Subject: Re: [RFC 3/4] drm/atomic-helper: Set fence deadline for vblank
Date: Tue, 27 Jul 2021 07:33:01 -0700 [thread overview]
Message-ID: <CAJs_Fx6dmNcjAvAJASr-YOZSDPrPfb0iwxNTZwmn1AQXpQevYQ@mail.gmail.com> (raw)
In-Reply-To: <db6cdec8-d44c-a09c-3fbd-60fb55c66efb@daenzer.net>
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
next prev parent reply other threads:[~2021-07-27 14:28 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-26 23:38 [RFC 0/4] dma-fence: Deadline awareness Rob Clark
2021-07-26 23:38 ` [RFC 1/4] dma-fence: Add deadline awareness Rob Clark
2021-07-27 7:11 ` Christian König
2021-07-27 14:25 ` Rob Clark
2021-07-28 7:03 ` Christian König
2021-07-28 11:37 ` Christian König
2021-07-28 15:15 ` Rob Clark
2021-07-28 17:23 ` Christian König
2021-07-28 17:58 ` Rob Clark
2021-07-29 7:03 ` Daniel Vetter
2021-07-29 15:23 ` Rob Clark
2021-07-29 16:18 ` Daniel Vetter
2021-07-29 17:32 ` Rob Clark
2021-07-26 23:38 ` [RFC 2/4] drm/vblank: Add helper to get next vblank time Rob Clark
2021-07-26 23:38 ` [RFC 3/4] drm/atomic-helper: Set fence deadline for vblank Rob Clark
2021-07-27 10:44 ` Michel Dänzer
2021-07-27 14:33 ` Rob Clark [this message]
2021-07-26 23:38 ` [RFC 4/4] drm/scheduler: Add fence deadline support Rob Clark
2021-07-26 23:51 ` [RFC 0/4] dma-fence: Deadline awareness Rob Clark
2021-07-27 14:41 ` Michel Dänzer
2021-07-27 15:12 ` Rob Clark
2021-07-27 15:19 ` Michel Dänzer
2021-07-27 15:37 ` Rob Clark
2021-07-28 11:36 ` Christian König
2021-07-28 13:08 ` Michel Dänzer
2021-07-28 13:13 ` Christian König
2021-07-28 13:24 ` Michel Dänzer
2021-07-28 13:31 ` Christian König
2021-07-28 13:57 ` Pekka Paalanen
2021-07-28 14:30 ` Christian König
2021-07-29 8:08 ` Michel Dänzer
2021-07-29 8:23 ` Pekka Paalanen
2021-07-29 8:43 ` Christian König
2021-07-29 9:15 ` Pekka Paalanen
2021-07-29 10:14 ` Christian König
2021-07-29 10:28 ` Michel Dänzer
2021-07-29 11:00 ` Pekka Paalanen
2021-07-29 11:43 ` Christian König
2021-07-29 12:49 ` Pekka Paalanen
2021-07-29 13:41 ` Christian König
2021-07-29 14:10 ` Pekka Paalanen
2021-07-28 15:27 ` Rob Clark
2021-07-28 17:20 ` Christian König
2021-07-28 15:34 ` Rob Clark
2021-07-29 7:09 ` Daniel Vetter
2021-07-29 8:17 ` Michel Dänzer
2021-07-29 9:03 ` Daniel Vetter
2021-07-29 9:37 ` Pekka Paalanen
2021-07-29 12:18 ` Daniel Vetter
2021-07-29 12:59 ` Pekka Paalanen
2021-07-29 14:05 ` Daniel Vetter
2021-07-27 21:17 ` [RFC 5/4] drm/msm: Add deadline based boost support Rob Clark
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