drm/amd/display: Keep linebuffer pixel depth at 30bpp for DCE-11.0.

Testing on AMD Carizzo with DCE-11.0 display engine showed that
it doesn't like a 36 bpp linebuffer very much. The display just
showed a solid green.

Testing on RavenRidge DCN-1.0, Polaris11 with DCE-11.2 and Kabini
with DCE-8.3 did not expose any problems, so for now only revert
to 30 bpp linebuffer depth on asics with DCE-11.0 display engine.

Fixes: a316db72096044 ("drm/amd/display: Increase linebuffer pixel depth to 36bpp.")
Reported-by: Tom StDenis <Tom.StDenis@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
index cd864cc..6d96fec 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -1042,9 +1042,16 @@ bool resource_build_scaling_params(struct pipe_ctx *pipe_ctx)
         * on certain displays, such as the Sharp 4k. 36bpp is needed
         * to support SURFACE_PIXEL_FORMAT_GRPH_ARGB16161616 and
         * SURFACE_PIXEL_FORMAT_GRPH_ABGR16161616 with actual > 10 bpc
-        * precision on at least DCN display engines.
+        * precision on at least DCN display engines. However, at least
+        * Carrizo with DCE_VERSION_11_0 does not like 36 bpp lb depth,
+        * so use only 30 bpp on DCE_VERSION_11_0. Testing with DCE 11.2 and 8.3
+        * did not show such problems, so this seems to be the exception.
         */
-       pipe_ctx->plane_res.scl_data.lb_params.depth = LB_PIXEL_DEPTH_36BPP;
+       if (plane_state->ctx->dce_version != DCE_VERSION_11_0)
+               pipe_ctx->plane_res.scl_data.lb_params.depth = LB_PIXEL_DEPTH_36BPP;
+       else
+               pipe_ctx->plane_res.scl_data.lb_params.depth = LB_PIXEL_DEPTH_30BPP;
+
        pipe_ctx->plane_res.scl_data.lb_params.alpha_en = plane_state->per_pixel_alpha;
 
        if (pipe_ctx->plane_res.xfm != NULL)