[PATCH 3/5] drm/i915/display/psr2: Fix cursor updates using legacy apis

[José Roberto de Souza]

The fast path only updates cursor register what will not cause
any updates in the screen when using PSR2 selective fetch.

The only option that we have is to go trough the slow patch that will
do full atomic commit, that will trigger the PSR2 selective fetch
compute and programing calls.

Without this patch is possible to see a mouse movement lag in Gnome
when PSR2 selective fetch is enabled.

Cc: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>
Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
---
 drivers/gpu/drm/i915/display/intel_cursor.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
index f61a25fb87e90..c7618fef01439 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -629,12 +629,16 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 
 	/*
 	 * When crtc is inactive or there is a modeset pending,
-	 * wait for it to complete in the slowpath
+	 * wait for it to complete in the slowpath.
+	 * PSR2 selective fetch also requires the slow path as
+	 * PSR2 plane and transcoder registers can only be updated during
+	 * vblank.
 	 *
 	 * FIXME bigjoiner fastpath would be good
 	 */
 	if (!crtc_state->hw.active || intel_crtc_needs_modeset(crtc_state) ||
-	    crtc_state->update_pipe || crtc_state->bigjoiner)
+	    crtc_state->update_pipe || crtc_state->bigjoiner ||
+	    crtc_state->enable_psr2_sel_fetch)
 		goto slow;
 
 	/*
-- 
2.32.0