[Intel-gfx] [PATCH] drm/i915/fbc: Remember to update FBC state even when not reallocating CFB

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

We mustn't forget to update our FBC state even if we don't have
to reallocate the CFB. Otherwise we won't refresh our notion
of what eg. the new fence or the new override CFB stride
should be. Using the wrong CFB stride in particular can cause
underruns and could even corrupt other stuff in stolen.

Fixes: f4cfdbb02ca8 ("drm/i915/fbc: Nuke state_cache")
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4774
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_fbc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
index 987ea4c4b5d0..465dc4e97ea8 100644
--- a/drivers/gpu/drm/i915/display/intel_fbc.c
+++ b/drivers/gpu/drm/i915/display/intel_fbc.c
@@ -1408,8 +1408,10 @@ static void __intel_fbc_enable(struct intel_atomic_state *state,
 		if (fbc->state.plane != plane)
 			return;
 
-		if (intel_fbc_is_ok(plane_state))
+		if (intel_fbc_is_ok(plane_state)) {
+			intel_fbc_update_state(state, crtc, plane);
 			return;
+		}
 
 		__intel_fbc_disable(fbc);
 	}
-- 
2.32.0