drm/atomic-helper: replace use of system_unbound_wq with system_dfl_wq

Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.

This lack of consistency cannot be addressed without refactoring the API.

system_unbound_wq should be the default workqueue so as not to enforce
locality constraints for random work whenever it's not required.

Adding system_dfl_wq to encourage its use when unbound work should be used.

The old system_unbound_wq will be kept for a few release cycles.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patch.msgid.link/20251030162043.292468-2-marco.crivellari@suse.com

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index cc1f0c102414f1e387a187b7f9d5beb162db2eb2..d422f79b96dbff318ff7626beee45fd7d13a47bb 100644 (file)
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2301,13 +2301,13 @@ int drm_atomic_helper_commit(struct drm_device *dev,
         * current layout.
         *
         * NOTE: Commit work has multiple phases, first hardware commit, then
-        * cleanup. We want them to overlap, hence need system_unbound_wq to
+        * cleanup. We want them to overlap, hence need system_dfl_wq to
         * make sure work items don't artificially stall on each another.
         */
 
        drm_atomic_state_get(state);
        if (nonblock)
-               queue_work(system_unbound_wq, &state->commit_work);
+               queue_work(system_dfl_wq, &state->commit_work);
        else
                commit_tail(state);
 
@@ -2340,7 +2340,7 @@ EXPORT_SYMBOL(drm_atomic_helper_commit);
  *
  * Asynchronous workers need to have sufficient parallelism to be able to run
  * different atomic commits on different CRTCs in parallel. The simplest way to
- * achieve this is by running them on the &system_unbound_wq work queue. Note
+ * achieve this is by running them on the &system_dfl_wq work queue. Note
  * that drivers are not required to split up atomic commits and run an
  * individual commit in parallel - userspace is supposed to do that if it cares.
  * But it might be beneficial to do that for modesets, since those necessarily