On Wed, Sep 24, 2025 at 03:03:39PM +0530, Nautiyal, Ankit K wrote:
>
> On 9/23/2025 7:43 PM, Ville Syrjälä wrote:
> > On Tue, Sep 23, 2025 at 06:40:39PM +0530, Ankit Nautiyal wrote:
> >> The helper intel_vrr_vblank_delay() is used to account for scl lines
> >> + extra_vblank_delay (for ICL/TGL case) for:
> >> - evasion logic for vrr case
> >> - to wait for SCL+ lines after send push operation.
> >>
> >> Rename the helper to intel_vrr_scl_delay since we are interested in the
> >> SCL+ lines for the VRR cases.
> >>
> >> Signed-off-by: Ankit Nautiyal <[email protected]>
> >> ---
> >> drivers/gpu/drm/i915/display/intel_dsb.c | 4 ++--
> >> drivers/gpu/drm/i915/display/intel_vblank.c | 2 +-
> >> drivers/gpu/drm/i915/display/intel_vrr.c | 2 +-
> >> drivers/gpu/drm/i915/display/intel_vrr.h | 2 +-
> >> 4 files changed, 5 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c
> >> b/drivers/gpu/drm/i915/display/intel_dsb.c
> >> index dee44d45b668..ca31e928ecb0 100644
> >> --- a/drivers/gpu/drm/i915/display/intel_dsb.c
> >> +++ b/drivers/gpu/drm/i915/display/intel_dsb.c
> >> @@ -128,7 +128,7 @@ static int dsb_vblank_delay(struct intel_atomic_state
> >> *state,
> >> * scanline until the delayed vblank occurs after
> >> * TRANS_PUSH has been written.
> >> */
> >> - return intel_vrr_vblank_delay(crtc_state) + 1;
> >> + return intel_vrr_scl_delay(crtc_state) + 1;
> > I'd skip this renaming for now. I think after you've added the
> > safe window scanline wait you can replace all of these with
> > crtc_state->set_context_latency.
>
> Hmm alright. I will drop this patch.
>
> But the intel_vrr_vblank_delay() is now just
> crtc_state->set_context_latency + intel_vrr_extra_vblank_delay().
>
> Do you mean we don't need intel_vrr_extra_vblank_delay()?
>
> Perhaps you are right, with the wait for vmin safe window to end, will
> leave only SCL lines before delayed vblank.
>
> So the one extra scanline which gets inserted for ICL/TGL will be
> counted in the wait for safe window.
Exactly. That icl/tgl quirk is functionally identical to
just reducing the guardband by one line on ADL+, and thus
both will be covered by the safe window wait.
>
>
> >
> >> else
> >> return intel_mode_vblank_delay(&crtc_state->hw.adjusted_mode);
> >> }
> >> @@ -723,7 +723,7 @@ void intel_dsb_vblank_evade(struct intel_atomic_state
> >> *state,
> >> intel_dsb_emit_wait_dsl(dsb, DSB_OPCODE_WAIT_DSL_OUT, 0, 0);
> >>
> >> if (pre_commit_is_vrr_active(state, crtc)) {
> >> - int vblank_delay = intel_vrr_vblank_delay(crtc_state);
> >> + int vblank_delay = intel_vrr_scl_delay(crtc_state);
> >>
> >> end = intel_vrr_vmin_vblank_start(crtc_state);
> >> start = end - vblank_delay - latency;
> >> diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c
> >> b/drivers/gpu/drm/i915/display/intel_vblank.c
> >> index c15234c1d96e..9441b7bacd27 100644
> >> --- a/drivers/gpu/drm/i915/display/intel_vblank.c
> >> +++ b/drivers/gpu/drm/i915/display/intel_vblank.c
> >> @@ -681,7 +681,7 @@ void intel_vblank_evade_init(const struct
> >> intel_crtc_state *old_crtc_state,
> >> else
> >> evade->vblank_start =
> >> intel_vrr_vmax_vblank_start(crtc_state);
> >>
> >> - vblank_delay = intel_vrr_vblank_delay(crtc_state);
> >> + vblank_delay = intel_vrr_scl_delay(crtc_state);
> > I was pondering about this case especially, but I *think* it should
> > also be changed to crtc_state->set_context_latency. We don't want to
> > perform the commit while in the SCL here because then we're not in
> > the safe window and the DSB we use for LUT updates wouldn't start
> > until the next safe window starts (== next frame's vactive), whereas
> > the double buffered registers would latch already in the upcoming
> > delayed vblank.
> >
> > But performing the commit while we're between undelayed vblank
> > and SCL start should be fine since that is part of the safe
> > window. So we don't need to evade the actual undelayed vblank
> > when in VRR mode.
> >
> > The only exception here would be the LRR and M/N cases since those
> > perhaps still need to evade the undlayed vblank proper. But we always
> > drop out of VRR mode for those types of updates so they won't be
> > taking this codepath anyway.
>
> Hmm ok so replacing intel_vrr_vblank_delay with
> crtc_state->set_context_latency will work for both:
>
> -the wait before push clear and
>
> -the evasion case
>
> So will add a last patch to just use crtc_state->set_context wherever we
> are using intel_vrr_vblank_delay then.
ack
--
Ville Syrjälä
Intel
