[RFC 2/7] drm: allow drm_wait_vblank_kernel() callback from workqueues

Paulo Zanoni przanoni at gmail.com
Wed Nov 19 11:47:10 PST 2014


From: Paulo Zanoni <paulo.r.zanoni at intel.com>

This is going to be needed by i915.ko, and I guess other drivers could
use it too.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/drm_irq.c           | 46 ++++++++++++++++++++++++++++++++-----
 drivers/gpu/drm/i915/i915_debugfs.c | 45 ++++++++++++++++++++++++++++--------
 include/drm/drmP.h                  | 11 ++++++++-
 3 files changed, 86 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index f031f77..099aef1 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -1108,6 +1108,22 @@ void drm_crtc_wait_one_vblank(struct drm_crtc *crtc)
 }
 EXPORT_SYMBOL(drm_crtc_wait_one_vblank);
 
+static void drm_wait_vblank_callback(struct drm_device *dev,
+				     struct drm_pending_vblank_event *e,
+				     unsigned long seq, struct timeval *now,
+				     bool premature)
+{
+	if (e->callback_from_work) {
+		e->callback_args.dev = dev;
+		e->callback_args.seq = seq;
+		e->callback_args.now = now;
+		e->callback_args.premature = premature;
+		schedule_work(&e->callback_work);
+	} else {
+		e->callback(dev, e, seq, now, premature);
+	}
+}
+
 /**
  * drm_vblank_off - disable vblank events on a CRTC
  * @dev: DRM device
@@ -1160,7 +1176,7 @@ void drm_vblank_off(struct drm_device *dev, int crtc)
 			  e->event.sequence, seq);
 		list_del(&e->base.link);
 		drm_vblank_put(dev, e->pipe);
-		e->callback(dev, e, seq, &now, true);
+		drm_wait_vblank_callback(dev, e, seq, &now, true);
 	}
 	spin_unlock_irqrestore(&dev->event_lock, irqflags);
 }
@@ -1372,9 +1388,20 @@ int drm_modeset_ctl(struct drm_device *dev, void *data,
 	return 0;
 }
 
+static void drm_vblank_event_work_func(struct work_struct *work)
+{
+	struct drm_pending_vblank_event *e =
+		container_of(work, struct drm_pending_vblank_event,
+			     callback_work);
+
+	e->callback(e->callback_args.dev, e, e->callback_args.seq,
+		    e->callback_args.now, e->callback_args.premature);
+}
+
 static int drm_queue_vblank_event(struct drm_device *dev, int pipe,
 				  union drm_wait_vblank *vblwait,
 				  struct drm_file *file_priv,
+				  bool callback_from_work,
 				  drm_vblank_callback_t callback)
 {
 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
@@ -1399,6 +1426,9 @@ static int drm_queue_vblank_event(struct drm_device *dev, int pipe,
 	e->base.file_priv = file_priv;
 	e->base.destroy = (void (*) (struct drm_pending_event *)) kfree;
 	e->callback = callback;
+	e->callback_from_work = callback_from_work;
+	if (callback_from_work)
+		INIT_WORK(&e->callback_work, drm_vblank_event_work_func);
 
 	spin_lock_irqsave(&dev->event_lock, flags);
 
@@ -1440,7 +1470,7 @@ static int drm_queue_vblank_event(struct drm_device *dev, int pipe,
 	e->event.sequence = vblwait->request.sequence;
 	if ((seq - vblwait->request.sequence) <= (1 << 23)) {
 		drm_vblank_put(dev, pipe);
-		e->callback(dev, e, seq, &now, false);
+		drm_wait_vblank_callback(dev, e, seq, &now, false);
 		vblwait->reply.sequence = seq;
 	} else {
 		/* drm_handle_vblank_events will call drm_vblank_put */
@@ -1477,6 +1507,7 @@ err_put:
 static int __drm_wait_vblank(struct drm_device *dev,
 			     union drm_wait_vblank *vblwait,
 			     struct drm_file *file_priv,
+			     bool callback_from_work,
 			     drm_vblank_callback_t callback)
 {
 	struct drm_vblank_crtc *vblank;
@@ -1533,7 +1564,7 @@ static int __drm_wait_vblank(struct drm_device *dev,
 		 * drm_vblank_put will be called asynchronously
 		 */
 		return drm_queue_vblank_event(dev, crtc, vblwait, file_priv,
-					      callback);
+					      callback_from_work, callback);
 	}
 
 	if ((flags & _DRM_VBLANK_NEXTONMISS) &&
@@ -1573,10 +1604,12 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data,
 {
 	union drm_wait_vblank *vblwait = data;
 
-	return __drm_wait_vblank(dev, vblwait, file_priv, send_vblank_event);
+	return __drm_wait_vblank(dev, vblwait, file_priv, false,
+				 send_vblank_event);
 }
 
 int drm_wait_vblank_kernel(struct drm_crtc *crtc, int count, bool absolute,
+			   bool callback_from_work,
 			   drm_vblank_callback_t callback,
 			   unsigned long user_data)
 {
@@ -1593,7 +1626,8 @@ int drm_wait_vblank_kernel(struct drm_crtc *crtc, int count, bool absolute,
 	vblwait.request.sequence = count;
 	vblwait.request.signal = user_data;
 
-	return __drm_wait_vblank(dev, &vblwait, NULL, callback);
+	return __drm_wait_vblank(dev, &vblwait, NULL, callback_from_work,
+				 callback);
 }
 EXPORT_SYMBOL(drm_wait_vblank_kernel);
 
@@ -1618,7 +1652,7 @@ static void drm_handle_vblank_events(struct drm_device *dev, int crtc)
 
 		list_del(&e->base.link);
 		drm_vblank_put(dev, e->pipe);
-		e->callback(dev, e, seq, &now, false);
+		drm_wait_vblank_callback(dev, e, seq, &now, false);
 	}
 
 	trace_drm_vblank_event(crtc, seq);
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index f989587..95cf6d3 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2718,6 +2718,7 @@ static int i915_ddb_info(struct seq_file *m, void *unused)
 struct vblank_data {
 	int eight;
 	const char *message;
+	bool can_sleep;
 };
 
 static void vblank_callback(struct drm_device *dev,
@@ -2727,6 +2728,7 @@ static void vblank_callback(struct drm_device *dev,
 {
 	struct vblank_data *data = (struct vblank_data *)e->event.user_data;
 
+	WARN_ON(data->can_sleep != drm_can_sleep());
 	WARN_ON(data->eight != 8);
 	DRM_DEBUG_KMS("vblank callback, seq: %lu, premature: %s message:%s\n",
 		      seq, yesno(premature), data->message);
@@ -2741,7 +2743,7 @@ static int i915_vblank_queue_test_new(struct seq_file *m, void *unused)
 	struct drm_device *dev = node->minor->dev;
 	struct intel_crtc *crtc = NULL;
 	int ret = 0;
-	struct vblank_data *data;
+	struct vblank_data *data1, *data2;
 
 	for_each_intel_crtc(dev, crtc)
 		if (crtc->pipe == PIPE_A)
@@ -2749,26 +2751,51 @@ static int i915_vblank_queue_test_new(struct seq_file *m, void *unused)
 	if (WARN_ON(!crtc))
 		return -EINVAL;
 
-	data = kzalloc(sizeof *data, GFP_KERNEL);
-	if (!data)
+	data1 = kzalloc(sizeof *data1, GFP_KERNEL);
+	if (!data1)
 		return -ENOMEM;
 
-	data->message = "hello world";
-	data->eight = 8;
+	data1->message = "hello world (atomic)";
+	data1->eight = 8;
+	data1->can_sleep = false;
+
+	data2 = kzalloc(sizeof *data2, GFP_KERNEL);
+	if (!data2) {
+		kfree(data1);
+		return -ENOMEM;
+	}
+
+	data2->message = "hello world (from work)";
+	data2->eight = 8;
+	data2->can_sleep = true;
 
 	DRM_DEBUG_KMS("waiting 60 vblanks (no callback)\n");
-	ret = drm_wait_vblank_kernel(&crtc->base, 60, false, NULL, 0);
+	ret = drm_wait_vblank_kernel(&crtc->base, 60, false, false, NULL, 0);
 	if (ret) {
 		DRM_DEBUG_KMS("vblank wait error: %d\n", ret);
+		kfree(data1);
+		kfree(data2);
 		return ret;
 	}
 	DRM_DEBUG_KMS("vblank wait done\n");
 
-	DRM_DEBUG_KMS("scheduling 60 vblanks (with callback)\n");
-	ret = drm_wait_vblank_kernel(&crtc->base, 60, false, vblank_callback,
-				     (unsigned long) data);
+	DRM_DEBUG_KMS("scheduling 60 vblanks (with callback, can't sleep)\n");
+	ret = drm_wait_vblank_kernel(&crtc->base, 60, false, false,
+				     vblank_callback, (unsigned long) data1);
+	if (ret) {
+		DRM_DEBUG_KMS("vblank schedule error: %d\n", ret);
+		kfree(data1);
+		kfree(data2);
+		return ret;
+	}
+	DRM_DEBUG_KMS("vblanks scheduled\n");
+
+	DRM_DEBUG_KMS("scheduling 60 vblanks (with callback, can sleep)\n");
+	ret = drm_wait_vblank_kernel(&crtc->base, 60, false, true,
+				     vblank_callback, (unsigned long) data2);
 	if (ret) {
 		DRM_DEBUG_KMS("vblank schedule error: %d\n", ret);
+		kfree(data2);
 		return ret;
 	}
 	DRM_DEBUG_KMS("vblanks scheduled\n");
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 39d0d87..bc114f0 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -669,7 +669,16 @@ struct drm_pending_vblank_event {
 	struct drm_pending_event base;
 	int pipe;
 	struct drm_event_vblank event;
+
 	drm_vblank_callback_t callback;
+	bool callback_from_work;
+	struct work_struct callback_work;
+	struct {
+		struct drm_device *dev;
+		unsigned long seq;
+		struct timeval *now;
+		bool premature;
+	} callback_args;
 };
 
 struct drm_vblank_crtc {
@@ -906,7 +915,7 @@ extern int drm_vblank_init(struct drm_device *dev, int num_crtcs);
 extern int drm_wait_vblank_ioctl(struct drm_device *dev, void *data,
 				 struct drm_file *filp);
 extern int drm_wait_vblank_kernel(struct drm_crtc *crtc, int count,
-				  bool absolute,
+				  bool absolute, bool callback_from_work,
 				  drm_vblank_callback_t callback,
 				  unsigned long user_data);
 extern u32 drm_vblank_count(struct drm_device *dev, int crtc);
-- 
2.1.1



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