drm/amd/display: Limit HW cursor size of >= 4k

[Description]
- For SubVP, we cannot support HW cursor if it's
  greater than 64 x 64 x 4 bytes in size
- However, on certain config changes (i.e. pixel format)
  we can exit SubVP (then change to HW cursor) then re-enter
  SubVP without changing back to SW cursor because there is
  no SetCursorAttributes call
- To workaround this issue, limit the HW cursor size to be
  less than 64 x 64 x 4 bytes whenever the stream is >= 4K
- Also ensure this W/A only affects DCN that supports SubVP
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Brian Chang <Brian.Chang@amd.com>
Signed-off-by: Alvin Lee <Alvin.Lee2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_stream.c

@@ -332,9 +332,21 @@ bool dc_stream_set_cursor_attributes(
 
 	dc = stream->ctx->dc;
 
-	if (dc->debug.allow_sw_cursor_fallback && attributes->height * attributes->width * 4 > 16384)
-		if (stream->mall_stream_config.type == SUBVP_MAIN)
+	/* SubVP is not compatible with HW cursor larger than 64 x 64 x 4.
+	 * Therefore, if cursor is greater than 64 x 64 x 4, fallback to SW cursor in the following case:
+	 * 1. For single display cases, if resolution is >= 5K and refresh rate < 120hz
+	 * 2. For multi display cases, if resolution is >= 4K and refresh rate < 120hz
+	 *
+	 * [< 120hz is a requirement for SubVP configs]
+	 */
+	if (dc->debug.allow_sw_cursor_fallback && attributes->height * attributes->width * 4 > 16384) {
+		if (dc->current_state->stream_count == 1 && stream->timing.v_addressable >= 2880 &&
+				((stream->timing.pix_clk_100hz * 100) / stream->timing.v_total / stream->timing.h_total) < 120)
 			return false;
+		else if (dc->current_state->stream_count > 1 && stream->timing.v_addressable >= 2160 &&
+				((stream->timing.pix_clk_100hz * 100) / stream->timing.v_total / stream->timing.h_total) < 120)
+			return false;
+	}
 
 	stream->cursor_attributes = *attributes;
 

drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource.c

@@ -723,7 +723,7 @@ static const struct dc_debug_options debug_defaults_drv = {
 	/* Must match enable_single_display_2to1_odm_policy to support dynamic ODM transitions*/
 	.enable_double_buffered_dsc_pg_support = true,
 	.enable_dp_dig_pixel_rate_div_policy = 1,
-	.allow_sw_cursor_fallback = false,
+	.allow_sw_cursor_fallback = false, // Linux can't do SW cursor "fallback"
 	.alloc_extra_way_for_cursor = true,
 	.min_prefetch_in_strobe_ns = 60000, // 60us
 };

drivers/gpu/drm/amd/display/dc/dcn321/dcn321_resource.c

@@ -721,7 +721,7 @@ static const struct dc_debug_options debug_defaults_drv = {
 	/*must match enable_single_display_2to1_odm_policy to support dynamic ODM transitions*/
 	.enable_double_buffered_dsc_pg_support = true,
 	.enable_dp_dig_pixel_rate_div_policy = 1,
-	.allow_sw_cursor_fallback = false,
+	.allow_sw_cursor_fallback = false, // Linux can't do SW cursor "fallback"
 	.alloc_extra_way_for_cursor = true,
 	.min_prefetch_in_strobe_ns = 60000, // 60us
 };