[PATCH 17/25] drm/amd/display: Do DC mode-change check when adding CRTCs

Harry Wentland harry.wentland at amd.com
Thu Nov 16 15:32:30 UTC 2017

From: "Leo (Sunpeng) Li" <sunpeng.li at amd.com>

Within atomic check, dm_update_crtcs_state is called twice. First to
remove from the dc_state, and subsequently to add to it.

In both calls, a secondary mode-change check is done using dc-level
states. We shouldn't be doing this while removing, since a new
dc_stream_state has not been created to do the necessary comparison.
Because of this, the mode_changed flag within the DRM state can be
mistakenly set to false. Doing so only when adding prevents this.

We are also guaranteed that a call to add will come after remove, or
else the atomic check fails (and a commit will not happen).

Signed-off-by: Leo (Sunpeng) Li <sunpeng.li at amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng at amd.com>
Acked-by: Harry Wentland <harry.wentland at amd.com>
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index d10f8c09469b..05bc98d74a33 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4535,7 +4535,7 @@ static int dm_update_crtcs_state(struct dc *dc,
-		if (dc_is_stream_unchanged(new_stream, dm_old_crtc_state->stream) &&
+		if (enable && dc_is_stream_unchanged(new_stream, dm_old_crtc_state->stream) &&
 				dc_is_stream_scaling_unchanged(new_stream, dm_old_crtc_state->stream)) {
 			new_crtc_state->mode_changed = false;

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