drm/i915: Fix ADL+ tiled plane stride when the POT stride is smaller than the original

commit 324b70e997aab0a7deab8cb90711faccda4e98c8 upstream.

plane_view_scanout_stride() currently assumes that we had to pad the
mapping stride with dummy pages in order to align it. But that is not
the case if the original fb stride exceeds the aligned stride used
to populate the remapped view, which is calculated from the user
specified framebuffer width rather than the user specified framebuffer
stride.

Ignore the original fb stride in this case and just stick to the POT
aligned stride. Getting this wrong will cause the plane to fetch the
wrong data, and can lead to fault errors if the page tables at the
bogus location aren't even populated.

TODO: figure out if this is OK for CCS, or if we should instead increase
the width of the view to cover the entire user specified fb stride
instead...

Cc: Imre Deak <imre.deak@intel.com>
Cc: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231204202443.31247-1-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
(cherry picked from commit 01a39f1c4f1220a4e6a25729fae87ff5794cbc52)
Cc: stable@vger.kernel.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/i915/display/intel_fb.c b/drivers/gpu/drm/i915/display/intel_fb.c
index 446bbf7..ca37f90 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_fb.c
+++ b/drivers/gpu/drm/i915/display/intel_fb.c
@@ -1370,7 +1370,8 @@ plane_view_scanout_stride(const struct intel_framebuffer *fb, int color_plane,
        struct drm_i915_private *i915 = to_i915(fb->base.dev);
        unsigned int stride_tiles;
 
-       if (IS_ALDERLAKE_P(i915) || DISPLAY_VER(i915) >= 14)
+       if ((IS_ALDERLAKE_P(i915) || DISPLAY_VER(i915) >= 14) &&
+           src_stride_tiles < dst_stride_tiles)
                stride_tiles = src_stride_tiles;
        else
                stride_tiles = dst_stride_tiles;