This is a note to let you know that I've just added the patch titled drm/i915: Don't zero out the Y plane's watermarks to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-i915-don-t-zero-out-the-y-plane-s-watermarks.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From bf52dc49ba0101f648b4c3ea26b812061406b0d4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@xxxxxxxxxxxxxxx> Date: Sat, 27 Mar 2021 02:59:45 +0200 Subject: drm/i915: Don't zero out the Y plane's watermarks MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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; Patches currently in stable-queue which might be from ville.syrjala@xxxxxxxxxxxxxxx are queue-5.11/drm-i915-don-t-zero-out-the-y-plane-s-watermarks.patch