linux-kernel - [PATCH 3/3] drm/msm/atomic: Convert to per-CRTC kthread

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Message-Id: <20201019211101.143327-4-robdclark@gmail.com>
Date:   Mon, 19 Oct 2020 14:10:53 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     linux-arm-msm@...r.kernel.org, Rob Clark <robdclark@...omium.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        freedreno@...ts.freedesktop.org (open list:DRM DRIVER FOR MSM ADRENO
        GPU), linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 3/3] drm/msm/atomic: Convert to per-CRTC kthread_work

From: Rob Clark <robdclark@...omium.org>

Use a SCHED_FIFO kthread_worker for async atomic commits.  We have a
hard deadline if we don't want to miss a frame.

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/msm/msm_atomic.c | 25 ++++++++++++++++++++-----
 drivers/gpu/drm/msm/msm_drv.h    |  3 ++-
 drivers/gpu/drm/msm/msm_kms.h    | 17 +++++++++++++----
 3 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c
index 561bfa48841c..484438f1e028 100644
--- a/drivers/gpu/drm/msm/msm_atomic.c
+++ b/drivers/gpu/drm/msm/msm_atomic.c
@@ -103,14 +103,13 @@ static enum hrtimer_restart msm_atomic_pending_timer(struct hrtimer *t)
 {
 	struct msm_pending_timer *timer = container_of(t,
 			struct msm_pending_timer, timer);
-	struct msm_drm_private *priv = timer->kms->dev->dev_private;
 
-	queue_work(priv->wq, &timer->work);
+	kthread_queue_work(timer->worker, &timer->work);
 
 	return HRTIMER_NORESTART;
 }
 
-static void msm_atomic_pending_work(struct work_struct *work)
+static void msm_atomic_pending_work(struct kthread_work *work)
 {
 	struct msm_pending_timer *timer = container_of(work,
 			struct msm_pending_timer, work);
@@ -118,14 +117,30 @@ static void msm_atomic_pending_work(struct work_struct *work)
 	msm_atomic_async_commit(timer->kms, timer->crtc_idx);
 }
 
-void msm_atomic_init_pending_timer(struct msm_pending_timer *timer,
+int msm_atomic_init_pending_timer(struct msm_pending_timer *timer,
 		struct msm_kms *kms, int crtc_idx)
 {
 	timer->kms = kms;
 	timer->crtc_idx = crtc_idx;
 	hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 	timer->timer.function = msm_atomic_pending_timer;
-	INIT_WORK(&timer->work, msm_atomic_pending_work);
+
+	timer->worker = kthread_create_worker(0, "atomic-worker-%d", crtc_idx);
+	if (IS_ERR(timer->worker)) {
+		int ret = PTR_ERR(timer->worker);
+		timer->worker = NULL;
+		return ret;
+	}
+	sched_set_fifo(timer->worker->task);
+	kthread_init_work(&timer->work, msm_atomic_pending_work);
+
+	return 0;
+}
+
+void msm_atomic_destroy_pending_timer(struct msm_pending_timer *timer)
+{
+	if (timer->worker)
+		kthread_destroy_worker(timer->worker);
 }
 
 static bool can_do_async(struct drm_atomic_state *state,
diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index 5308e636a90c..f869ed67b5da 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -235,8 +235,9 @@ struct msm_pending_timer;
 
 int msm_atomic_prepare_fb(struct drm_plane *plane,
 			  struct drm_plane_state *new_state);
-void msm_atomic_init_pending_timer(struct msm_pending_timer *timer,
+int msm_atomic_init_pending_timer(struct msm_pending_timer *timer,
 		struct msm_kms *kms, int crtc_idx);
+void msm_atomic_destroy_pending_timer(struct msm_pending_timer *timer);
 void msm_atomic_commit_tail(struct drm_atomic_state *state);
 struct drm_atomic_state *msm_atomic_state_alloc(struct drm_device *dev);
 void msm_atomic_state_clear(struct drm_atomic_state *state);
diff --git a/drivers/gpu/drm/msm/msm_kms.h b/drivers/gpu/drm/msm/msm_kms.h
index 0be9e6487556..26321c13f950 100644
--- a/drivers/gpu/drm/msm/msm_kms.h
+++ b/drivers/gpu/drm/msm/msm_kms.h
@@ -136,7 +136,8 @@ struct msm_kms;
  */
 struct msm_pending_timer {
 	struct hrtimer timer;
-	struct work_struct work;
+	struct kthread_work work;
+	struct kthread_worker *worker;
 	struct msm_kms *kms;
 	unsigned crtc_idx;
 };
@@ -163,19 +164,27 @@ struct msm_kms {
 static inline int msm_kms_init(struct msm_kms *kms,
 		const struct msm_kms_funcs *funcs)
 {
-	unsigned i;
+	unsigned i, ret;
 
 	mutex_init(&kms->commit_lock);
 	kms->funcs = funcs;
 
-	for (i = 0; i < ARRAY_SIZE(kms->pending_timers); i++)
-		msm_atomic_init_pending_timer(&kms->pending_timers[i], kms, i);
+	for (i = 0; i < ARRAY_SIZE(kms->pending_timers); i++) {
+		ret = msm_atomic_init_pending_timer(&kms->pending_timers[i], kms, i);
+		if (ret) {
+			return ret;
+		}
+	}
 
 	return 0;
 }
 
 static inline void msm_kms_destroy(struct msm_kms *kms)
 {
+	unsigned i;
+
+	for (i = 0; i < ARRAY_SIZE(kms->pending_timers); i++)
+		msm_atomic_destroy_pending_timer(&kms->pending_timers[i]);
 }
 
 struct msm_kms *mdp4_kms_init(struct drm_device *dev);
-- 
2.26.2