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Subject[PATCH 5.2 07/45] drm/amd/display: Skip determining update type for async updates
Date
From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>

commit 43d10d30df156f7834fa91aecb69614fefc8bb0a upstream.

[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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 27 ++++++++++++++++------
1 file changed, 20 insertions(+), 7 deletions(-)

--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -6788,6 +6788,26 @@ static int amdgpu_dm_atomic_check(struct
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
@@ -6840,13 +6860,6 @@ static int amdgpu_dm_atomic_check(struct
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 */

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