drm/amd/display: Skip determining update type for async updates

[Why]
By passing through the dm_determine_update_type_for_commit for atomic
commits that can be done asynchronously we are incurring a
performance penalty by locking access to the global private object
and holding that access until the end of the programming sequence.

This is also allocating a new large dc_state on every access in addition
to retaining all the references on each stream and plane until the end
of the programming sequence.

[How]
Shift the determination for async update before validation. Return early
if it's going to be an async update.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: David Francis <david.francis@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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 a833b23f34ab4e7bc716da2091e2b3b47c38bf46..511480df7e6303a777d3f97252158976ac3e02f6 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -7275,6 +7275,26 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
        if (ret)
                goto fail;
 
+       if (state->legacy_cursor_update) {
+               /*
+                * This is a fast cursor update coming from the plane update
+                * helper, check if it can be done asynchronously for better
+                * performance.
+                */
+               state->async_update =
+                       !drm_atomic_helper_async_check(dev, state);
+
+               /*
+                * Skip the remaining global validation if this is an async
+                * update. Cursor updates can be done without affecting
+                * state or bandwidth calcs and this avoids the performance
+                * penalty of locking the private state object and
+                * allocating a new dc_state.
+                */
+               if (state->async_update)
+                       return 0;
+       }
+
        /* Check scaling and underscan changes*/
        /* TODO Removed scaling changes validation due to inability to commit
         * new stream into context w\o causing full reset. Need to
@@ -7327,13 +7347,6 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
                        ret = -EINVAL;
                        goto fail;
                }
-       } else if (state->legacy_cursor_update) {
-               /*
-                * This is a fast cursor update coming from the plane update
-                * helper, check if it can be done asynchronously for better
-                * performance.
-                */
-               state->async_update = !drm_atomic_helper_async_check(dev, state);
        }
 
        /* Must be success */