[PATCH v8 12/13] drm/i915/display: Ensure we have "Frame Change" event in DSB commit

["Jouni Högander" <jouni.hogander@intel.com>]

We may have commit which doesn't have any non-arming plane register
writes. In that case there aren't "Frame Change" event before DSB vblank
evasion which hangs as PIPEDSL register is reading as 0 when PSR state is
SRDENT(PSR1) or DEEP_SLEEP(PSR2). Handle this by ensuring "Frame Change"
event at the begin of DSB commit if using PSR/PR.

v3: dsb_commit as a first parameter
v2: use intel_psr_trigger_frame_change_event

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index dbb8dc318471..f0cfd291eba5 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -7737,6 +7737,14 @@ static void intel_atomic_dsb_finish(struct intel_atomic_state *state,
 		intel_crtc_planes_update_noarm(new_crtc_state->dsb_commit,
 					       state, crtc);
 
+		/*
+		 * Ensure we have "Frame Change" event when PSR state is
+		 * SRDENT(PSR1) or DEEP_SLEEP(PSR2). Otherwise DSB vblank
+		 * evasion hangs as PIPEDSL is reading as 0.
+		 */
+		intel_psr_trigger_frame_change_event(new_crtc_state->dsb_commit,
+						     state, crtc);
+
 		intel_dsb_vblank_evade(state, new_crtc_state->dsb_commit);
 
 		if (intel_crtc_needs_color_update(new_crtc_state))
-- 
2.43.0