drm/amd/display: check if modeset is required before adding plane

Adding affected planes without checking if modeset is requested from the user space causes performance regression in video p/b scenarios when full screen p/b is not composited.

Hence add a check before adding a plane as affected.

bug: https://bugs.freedesktop.org/show_bug.cgi?id=103408

Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Shirish S <shirish.s@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -4653,6 +4653,9 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 		}
 	} else {
 		for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
+			if (!drm_atomic_crtc_needs_modeset(new_crtc_state))
+				continue;
+
 			if (!new_crtc_state->enable)
 				continue;