On Tue, Feb 21, 2023 at 1:48 PM Ville Syrjälä <ville.syrj...@linux.intel.com> wrote: > > On Tue, Feb 21, 2023 at 11:39:40PM +0200, Ville Syrjälä wrote: > > On Tue, Feb 21, 2023 at 11:54:55AM -0800, Rob Clark wrote: > > > On Tue, Feb 21, 2023 at 5:01 AM Ville Syrjälä > > > <ville.syrj...@linux.intel.com> wrote: > > > > > > > > On Tue, Feb 21, 2023 at 10:45:51AM +0200, Pekka Paalanen wrote: > > > > > On Mon, 20 Feb 2023 07:55:41 -0800 > > > > > Rob Clark <robdcl...@gmail.com> wrote: > > > > > > > > > > > On Mon, Feb 20, 2023 at 1:08 AM Pekka Paalanen > > > > > > <ppaala...@gmail.com> wrote: > > > > > > > > > > > > > > On Sat, 18 Feb 2023 13:15:53 -0800 > > > > > > > Rob Clark <robdcl...@gmail.com> wrote: > > > > > > > > > > > > > > > From: Rob Clark <robdcl...@chromium.org> > > > > > > > > > > > > > > > > Will be used in the next commit to set a deadline on fences > > > > > > > > that an > > > > > > > > atomic update is waiting on. > > > > > > > > > > > > > > > > Signed-off-by: Rob Clark <robdcl...@chromium.org> > > > > > > > > --- > > > > > > > > drivers/gpu/drm/drm_vblank.c | 32 > > > > > > > > ++++++++++++++++++++++++++++++++ > > > > > > > > include/drm/drm_vblank.h | 1 + > > > > > > > > 2 files changed, 33 insertions(+) > > > > > > > > > > > > > > > > diff --git a/drivers/gpu/drm/drm_vblank.c > > > > > > > > b/drivers/gpu/drm/drm_vblank.c > > > > > > > > index 2ff31717a3de..caf25ebb34c5 100644 > > > > > > > > --- a/drivers/gpu/drm/drm_vblank.c > > > > > > > > +++ b/drivers/gpu/drm/drm_vblank.c > > > > > > > > @@ -980,6 +980,38 @@ u64 drm_crtc_vblank_count_and_time(struct > > > > > > > > drm_crtc *crtc, > > > > > > > > } > > > > > > > > EXPORT_SYMBOL(drm_crtc_vblank_count_and_time); > > > > > > > > > > > > > > > > +/** > > > > > > > > + * drm_crtc_next_vblank_time - calculate the time of the next > > > > > > > > vblank > > > > > > > > + * @crtc: the crtc for which to calculate next vblank time > > > > > > > > + * @vblanktime: pointer to time to receive the next vblank > > > > > > > > timestamp. > > > > > > > > + * > > > > > > > > + * Calculate the expected time of the next vblank based on > > > > > > > > time of previous > > > > > > > > + * vblank and frame duration > > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > for VRR this targets the highest frame rate possible for the > > > > > > > current > > > > > > > VRR mode, right? > > > > > > > > > > > > > > > > > > > It is based on vblank->framedur_ns which is in turn based on > > > > > > mode->crtc_clock. Presumably for VRR that ends up being a maximum? > > > > > > > > > > I don't know. :-) > > > > > > > > At least for i915 this will give you the maximum frame > > > > duration. > > > > > > > > Also this does not calculate the the start of vblank, it > > > > calculates the start of active video. > > > > > > AFAIU, vsync_end/vsync_start are in units of line, so I could do > > > something like: > > > > > > vsync_lines = vblank->hwmode.vsync_end - vblank->hwmode.vsync_start; > > > vsyncdur = ns_to_ktime(vblank->linedur_ns * vsync_lines); > > > framedur = ns_to_ktime(vblank->framedur_ns); > > > *vblanktime = ktime_add(*vblanktime, ktime_sub(framedur, vsyncdur)); > > > > Something like this should work: > > vblank_start = framedur_ns * crtc_vblank_start / crtc_vtotal > > deadline = vblanktime + vblank_start > > > > That would be the expected time when the next start of vblank > > happens. > > Except that drm_vblank_count_and_time() will give you the last > sampled timestamp, which may be long ago in the past. Would > need to add an _accurate version of that if we want to be > guaranteed a fresh sample.
IIRC the only time we wouldn't have a fresh sample is if the screen has been idle for some time? In which case, I think that doesn't matter. BR, -R > > -- > Ville Syrjälä > Intel
