On Fri, Jan 24, 2025 at 12:56:22PM +0200, Jouni Högander wrote:
> PIPEDSL is reading as 0 when in SRDENT(PSR1) or DEEP_SLEEP(PSR2). On
> wake-up scanline counting starts from vblank_start - 1. We don't know if
> wake-up is already ongoing when evasion starts. In worst case PIPEDSL could
> start reading valid value right after checking the scanline. In this
> scenario we wouldn't have enough time to write all registers. To tackle
> this evade scanline 0 as well. As a drawback we have 1 frame delay in flip
> when waking up.
>
> Signed-off-by: Jouni Högander <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_dsb.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c
> b/drivers/gpu/drm/i915/display/intel_dsb.c
> index bb77ded8bf726..914f0be4491c4 100644
> --- a/drivers/gpu/drm/i915/display/intel_dsb.c
> +++ b/drivers/gpu/drm/i915/display/intel_dsb.c
> @@ -528,6 +528,18 @@ void intel_dsb_vblank_evade(struct intel_atomic_state
> *state,
> int latency = intel_usecs_to_scanlines(&crtc_state->hw.adjusted_mode,
> 20);
> int start, end;
>
> + /*
> + * PIPEDSL is reading as 0 when in SRDENT(PSR1) or DEEP_SLEEP(PSR2). On
> + * wake-up scanline counting starts from vblank_start - 1. We don't know
> + * if wake-up is already ongoing when evasion starts. In worst case
> + * PIPEDSL could start reading valid value right after checking the
> + * scanline. In this scenario we wouldn't have enough time to write all
> + * registers. To tackle this evade scanline 0 as well. As a drawback we
> + * have 1 frame delay in flip when waking up.
> + */
> + if (crtc_state->has_psr && !crtc_state->has_panel_replay)
What's the deal with panel replay here?
> + intel_dsb_wait_scanline_out(state, dsb, 0, 0);
This needs to be a raw
intel_dsb_emit_wait_dsl(dsb, DSB_OPCODE_WAIT_DSL_OUT, 0, 0)
because we need to evade the hw scanline 0. What the software
thinks is scanline 0 is a bit different (see scanline_offset).
> +
> if (pre_commit_is_vrr_active(state, crtc)) {
> int vblank_delay = intel_vrr_vblank_delay(crtc_state);
>
> --
> 2.43.0
--
Ville Syrjälä
Intel
