[PATCH v2 2/3] usb: gadget: uvc: increase worker prio to WQ_HIGHPRI

[Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>]

Likewise to the uvcvideo hostside driver, this patch is changing the
simple workqueue to an async_wq with higher priority. This ensures that
the worker will not be scheduled away while the video stream is handled.

Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>

---
v1 -> v2: - added destroy_workqueue in uvc_function_unbind
          - reworded comment above allow_workqueue

 drivers/usb/gadget/function/f_uvc.c     | 4 ++++
 drivers/usb/gadget/function/uvc.h       | 1 +
 drivers/usb/gadget/function/uvc_v4l2.c  | 2 +-
 drivers/usb/gadget/function/uvc_video.c | 9 +++++++--
 4 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index 0334c8a414e9b9..02e0caecaada1a 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -891,9 +891,13 @@ static void uvc_function_unbind(struct usb_configuration *c,
 {
 	struct usb_composite_dev *cdev = c->cdev;
 	struct uvc_device *uvc = to_uvc(f);
+	struct uvc_video *video = &uvc->video;
 
 	uvcg_info(f, "%s()\n", __func__);
 
+	if (video->async_wq)
+		destroy_workqueue(video->async_wq);
+
 	device_remove_file(&uvc->vdev.dev, &dev_attr_function_name);
 	video_unregister_device(&uvc->vdev);
 	v4l2_device_unregister(&uvc->v4l2_dev);
diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h
index 9eec104b3666ad..2bc43ce20e25a5 100644
--- a/drivers/usb/gadget/function/uvc.h
+++ b/drivers/usb/gadget/function/uvc.h
@@ -87,6 +87,7 @@ struct uvc_video {
 	struct usb_ep *ep;
 
 	struct work_struct pump;
+	struct workqueue_struct *async_wq;
 
 	/* Frame parameters */
 	u8 bpp;
diff --git a/drivers/usb/gadget/function/uvc_v4l2.c b/drivers/usb/gadget/function/uvc_v4l2.c
index a2c78690c5c288..9b1488f7abd736 100644
--- a/drivers/usb/gadget/function/uvc_v4l2.c
+++ b/drivers/usb/gadget/function/uvc_v4l2.c
@@ -170,7 +170,7 @@ uvc_v4l2_qbuf(struct file *file, void *fh, struct v4l2_buffer *b)
 		return ret;
 
 	if (uvc->state == UVC_STATE_STREAMING)
-		schedule_work(&video->pump);
+		queue_work(video->async_wq, &video->pump);
 
 	return ret;
 }
diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c
index a9bb4553db847e..9a9101851bc1e8 100644
--- a/drivers/usb/gadget/function/uvc_video.c
+++ b/drivers/usb/gadget/function/uvc_video.c
@@ -277,7 +277,7 @@ uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
 	spin_unlock_irqrestore(&video->req_lock, flags);
 
 	if (uvc->state == UVC_STATE_STREAMING)
-		schedule_work(&video->pump);
+		queue_work(video->async_wq, &video->pump);
 }
 
 static int
@@ -478,7 +478,7 @@ int uvcg_video_enable(struct uvc_video *video, int enable)
 
 	video->req_int_count = 0;
 
-	schedule_work(&video->pump);
+	queue_work(video->async_wq, &video->pump);
 
 	return ret;
 }
@@ -492,6 +492,11 @@ int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc)
 	spin_lock_init(&video->req_lock);
 	INIT_WORK(&video->pump, uvcg_video_pump);
 
+	/* Allocate a work queue for asynchronous video pump handler. */
+	video->async_wq = alloc_workqueue("uvcvideo", WQ_UNBOUND | WQ_HIGHPRI, 0);
+	if (!video->async_wq)
+		return -EINVAL;
+
 	video->uvc = uvc;
 	video->fcc = V4L2_PIX_FMT_YUYV;
 	video->bpp = 16;
-- 
2.30.2