drm/amd/display: Fix crash during MPO + ODM combine mode recalculation

[Why]
When calculating recout width for an MPO plane on a mode that's using
ODM combine, driver can calculate a negative value, resulting in a
crash.

[How]
For negative widths, use zero such that validation will prune the
configuration correctly and disallow MPO.

Signed-off-by: Aric Cyr <[email protected]>
Reviewed-by: Krunoslav Kovac <[email protected]>
Acked-by: Stylon Wang <[email protected]>
Tested-by: Daniel Wheeler <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: AMD-aric

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

@@ -799,6 +799,11 @@ static void calculate_recout(struct pipe_ctx *pipe_ctx)
 			if (split_idx == split_count) {
 				/* rightmost pipe is the remainder recout */
 				data->recout.width -= data->h_active * split_count - data->recout.x;
+
+				/* ODM combine cases with MPO we can get negative widths */
+				if (data->recout.width < 0)
+					data->recout.width = 0;
+
 				data->recout.x = 0;
 			} else
 				data->recout.width = data->h_active - data->recout.x;