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Subject[PATCH v2 2/3] drm/atomic: Use kthread worker for nonblocking commits
Date
From: Rob Clark <robdclark@chromium.org>

This will allow us to more easily switch scheduling rules based on what
userspace wants.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
drivers/gpu/drm/drm_atomic_helper.c | 13 ++++++++----
include/drm/drm_atomic.h | 31 +++++++++++++++++++++++++++++
2 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 9e1ad493e689..75eeec5e7b10 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1659,11 +1659,11 @@ static void commit_tail(struct drm_atomic_state *old_state)
drm_atomic_state_put(old_state);
}

-static void commit_work(struct work_struct *work)
+static void commit_work(struct kthread_work *work)
{
struct drm_atomic_state *state = container_of(work,
struct drm_atomic_state,
- commit_work);
+ commit_kwork);
commit_tail(state);
}

@@ -1797,6 +1797,7 @@ int drm_atomic_helper_commit(struct drm_device *dev,
struct drm_atomic_state *state,
bool nonblock)
{
+ struct kthread_worker *worker = NULL;
int ret;

if (state->async_update) {
@@ -1814,7 +1815,7 @@ int drm_atomic_helper_commit(struct drm_device *dev,
if (ret)
return ret;

- INIT_WORK(&state->commit_work, commit_work);
+ kthread_init_work(&state->commit_kwork, commit_work);

ret = drm_atomic_helper_prepare_planes(dev, state);
if (ret)
@@ -1857,8 +1858,12 @@ int drm_atomic_helper_commit(struct drm_device *dev,
*/

drm_atomic_state_get(state);
+
if (nonblock)
- queue_work(system_unbound_wq, &state->commit_work);
+ worker = drm_atomic_pick_worker(state);
+
+ if (worker)
+ kthread_queue_work(worker, &state->commit_kwork);
else
commit_tail(state);

diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index d07c851d255b..8d0ee19953df 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -373,8 +373,18 @@ struct drm_atomic_state {
*
* Work item which can be used by the driver or helpers to execute the
* commit without blocking.
+ *
+ * This is deprecated, use commit_kwork.
*/
struct work_struct commit_work;
+
+ /**
+ * @commit_kwork:
+ *
+ * Work item which can be used by the driver or helpers to execute the
+ * commit without blocking.
+ */
+ struct kthread_work commit_kwork;
};

void __drm_crtc_commit_free(struct kref *kref);
@@ -954,6 +964,27 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
(new_obj_state) = (__state)->private_objs[__i].new_state, 1); \
(__i)++)

+/**
+ * drm_atomic_pick_worker - helper to get kworker to use for nonblocking commit
+ * @state: the &drm_atomic_state for the commit
+ *
+ * Pick an appropriate worker for a given atomic update. The first CRTC
+ * invovled in the atomic update is used to pick the worker, to prevent
+ * serializing multiple pageflips / atomic-updates on indenpendent CRTCs.
+ */
+static inline struct kthread_worker *
+drm_atomic_pick_worker(const struct drm_atomic_state *state)
+{
+ struct drm_crtc_state *crtc_state;
+ struct drm_crtc *crtc;
+ unsigned i;
+
+ for_each_new_crtc_in_state(state, crtc, crtc_state, i)
+ return crtc->worker;
+
+ return NULL;
+}
+
/**
* drm_atomic_crtc_needs_modeset - compute combined modeset need
* @state: &drm_crtc_state for the CRTC
--
2.26.2
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