[Intel-gfx] [PATCH] drm/i915: Fix remapped stride with CCS on ADL+

[Ville Syrjala]

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

On ADL+ the hardware automagically calculates the CCS AUX surface
stride from the main surface stride, so when remapping we can't
really play a lot of tricks with the main surface stride, or else
the AUX surface stride would get miscalculated and no longer
match the actual data layout in memory.

Supposedly we could remap in 256 main surface tile units
(AUX page(4096)/cachline(64)*4(4x1 main surface tiles per
AUX cacheline)=256 main surface tiles), but the extra complexity
is probably not worth the hassle.

So let's just make sure our mapping stride is calculated from
the full framebuffer stride (instead of the framebuffer width).
This way the stride we program into PLANE_STRIDE will be the
original framebuffer stride, and thus there will be no change
to the AUX stride/layout.

Cc: Imre Deak <imre.deak at intel.com>
Cc: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_fb.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_fb.c b/drivers/gpu/drm/i915/display/intel_fb.c
index ab634a4c86d1..9f35bdce3eb8 100644
--- a/drivers/gpu/drm/i915/display/intel_fb.c
+++ b/drivers/gpu/drm/i915/display/intel_fb.c
@@ -1509,8 +1509,20 @@ static u32 calc_plane_remap_info(const struct intel_framebuffer *fb, int color_p
 
 			size += remap_info->size;
 		} else {
-			unsigned int dst_stride = plane_view_dst_stride_tiles(fb, color_plane,
-									      remap_info->width);
+			unsigned int dst_stride;
+
+			/*
+			 * The hardware automagically calculates the CCS AUX surface
+			 * stride from the main surface stride so can't really remap a
+			 * smaller subset (unless we'd remap in whole AUX page units).
+			 */
+			if (intel_fb_needs_pot_stride_remap(fb) &&
+			    intel_fb_is_ccs_modifier(fb->base.modifier))
+				dst_stride = remap_info->src_stride;
+			else
+				dst_stride = remap_info->width;
+
+			dst_stride = plane_view_dst_stride_tiles(fb, color_plane, dst_stride);
 
 			assign_chk_ovf(i915, remap_info->dst_stride, dst_stride);
 			color_plane_info->mapping_stride = dst_stride *
-- 
2.41.0