drm: use workqueue instead of slow-work

Workqueue can now handle high concurrency.  Convert drm_crtc_helper to
use system_nrt_wq instead of slow-work.  The conversion is mostly
straight forward.  One difference is that drm_helper_hpd_irq_event()
no longer blocks and can be called from any context.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org

drivers/gpu/drm/drm_crtc_helper.c

@@ -808,13 +808,11 @@ int drm_helper_resume_force_mode(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_helper_resume_force_mode);
 
-static struct slow_work_ops output_poll_ops;
-
 #define DRM_OUTPUT_POLL_PERIOD (10*HZ)
-static void output_poll_execute(struct slow_work *work)
+static void output_poll_execute(struct work_struct *work)
 {
-	struct delayed_slow_work *delayed_work = container_of(work, struct delayed_slow_work, work);
-	struct drm_device *dev = container_of(delayed_work, struct drm_device, mode_config.output_poll_slow_work);
+	struct delayed_work *delayed_work = to_delayed_work(work);
+	struct drm_device *dev = container_of(delayed_work, struct drm_device, mode_config.output_poll_work);
 	struct drm_connector *connector;
 	enum drm_connector_status old_status, status;
 	bool repoll = false, changed = false;
@@ -854,7 +852,7 @@ static void output_poll_execute(struct slow_work *work)
 	}
 
 	if (repoll) {
-		ret = delayed_slow_work_enqueue(delayed_work, DRM_OUTPUT_POLL_PERIOD);
+		ret = queue_delayed_work(system_nrt_wq, delayed_work, DRM_OUTPUT_POLL_PERIOD);
 		if (ret)
 			DRM_ERROR("delayed enqueue failed %d\n", ret);
 	}
@@ -864,7 +862,7 @@ void drm_kms_helper_poll_disable(struct drm_device *dev)
 {
 	if (!dev->mode_config.poll_enabled)
 		return;
-	delayed_slow_work_cancel(&dev->mode_config.output_poll_slow_work);
+	cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
 }
 EXPORT_SYMBOL(drm_kms_helper_poll_disable);
 
@@ -880,7 +878,7 @@ void drm_kms_helper_poll_enable(struct drm_device *dev)
 	}
 
 	if (poll) {
-		ret = delayed_slow_work_enqueue(&dev->mode_config.output_poll_slow_work, DRM_OUTPUT_POLL_PERIOD);
+		ret = queue_delayed_work(system_nrt_wq, &dev->mode_config.output_poll_work, DRM_OUTPUT_POLL_PERIOD);
 		if (ret)
 			DRM_ERROR("delayed enqueue failed %d\n", ret);
 	}
@@ -889,9 +887,7 @@ EXPORT_SYMBOL(drm_kms_helper_poll_enable);
 
 void drm_kms_helper_poll_init(struct drm_device *dev)
 {
-	slow_work_register_user(THIS_MODULE);
-	delayed_slow_work_init(&dev->mode_config.output_poll_slow_work,
-			       &output_poll_ops);
+	INIT_DELAYED_WORK(&dev->mode_config.output_poll_work, output_poll_execute);
 	dev->mode_config.poll_enabled = true;
 
 	drm_kms_helper_poll_enable(dev);
@@ -901,7 +897,6 @@ EXPORT_SYMBOL(drm_kms_helper_poll_init);
 void drm_kms_helper_poll_fini(struct drm_device *dev)
 {
 	drm_kms_helper_poll_disable(dev);
-	slow_work_unregister_user(THIS_MODULE);
 }
 EXPORT_SYMBOL(drm_kms_helper_poll_fini);
 
@@ -909,12 +904,8 @@ void drm_helper_hpd_irq_event(struct drm_device *dev)
 {
 	if (!dev->mode_config.poll_enabled)
 		return;
-	delayed_slow_work_cancel(&dev->mode_config.output_poll_slow_work);
-	/* schedule a slow work asap */
-	delayed_slow_work_enqueue(&dev->mode_config.output_poll_slow_work, 0);
+	/* kill timer and schedule immediate execution, this doesn't block */
+	cancel_delayed_work(&dev->mode_config.output_poll_work);
+	queue_delayed_work(system_nrt_wq, &dev->mode_config.output_poll_work, 0);
 }
 EXPORT_SYMBOL(drm_helper_hpd_irq_event);
-
-static struct slow_work_ops output_poll_ops = {
-	.execute = output_poll_execute,
-};

include/drm/drm_crtc.h

@@ -31,7 +31,6 @@
 #include <linux/idr.h>
 
 #include <linux/fb.h>
-#include <linux/slow-work.h>
 
 struct drm_device;
 struct drm_mode_set;
@@ -595,7 +594,7 @@ struct drm_mode_config {
 
 	/* output poll support */
 	bool poll_enabled;
-	struct delayed_slow_work output_poll_slow_work;
+	struct delayed_work output_poll_work;
 
 	/* pointers to standard properties */
 	struct list_head property_blob_list;