[PATCH 5.11 061/122] drm/i915: Dont zero out the Y planes watermarks

[Greg Kroah-Hartman]

From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>

commit bf52dc49ba0101f648b4c3ea26b812061406b0d4 upstream.

Don't zero out the watermarks for the Y plane since we've already
computed them when computing the UV plane's watermarks (since the
UV plane always appears before ethe Y plane when iterating through
the planes).

This leads to allocating no DDB for the Y plane since .min_ddb_alloc
also gets zeroed. And that of course leads to underruns when scanning
out planar formats.

Cc: stable@xxxxxxxxxxxxxxx
Cc: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
Fixes: dbf71381d733 ("drm/i915: Nuke intel_atomic_crtc_state_for_each_plane_state() from skl+ wm code")
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20210327005945.4929-1-ville.syrjala@xxxxxxxxxxxxxxx
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
(cherry picked from commit f99b805fb9413ff007ca0b6add871737664117dd)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/intel_pm.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5539,12 +5539,12 @@ static int icl_build_plane_wm(struct int
 	struct skl_plane_wm *wm = &crtc_state->wm.skl.raw.planes[plane_id];
 	int ret;
 
-	memset(wm, 0, sizeof(*wm));
-
 	/* Watermarks calculated in master */
 	if (plane_state->planar_slave)
 		return 0;
 
+	memset(wm, 0, sizeof(*wm));
+
 	if (plane_state->planar_linked_plane) {
 		const struct drm_framebuffer *fb = plane_state->hw.fb;
 		enum plane_id y_plane_id = plane_state->planar_linked_plane->id;