Commit 9b91a652 authored by Michal Grzeschik's avatar Michal Grzeschik Committed by Greg Kroah-Hartman
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usb: gadget: uvc: increase worker prio to WQ_HIGHPRI 



This patch is changing the simple workqueue in the gadget driver to be
allocated as async_wq with a higher priority. The pump worker, that is
filling the usb requests, will have a higher priority and will not be
scheduled away so often while the video stream is handled. This will
lead to fewer streaming underruns.

Signed-off-by: default avatarMichael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20220907215818.2670097-1-m.grzeschik@pengutronix.de


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d818320e

drivers/usb/gadget/function/f_uvc.c

+4 −0
Original line number Diff line number Diff line
@@ -897,10 +897,14 @@ 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;

	long wait_ret = 1;



	uvcg_info(f, "%s()\n", __func__);



	if (video->async_wq)

		destroy_workqueue(video->async_wq);



	/*

	 * If we know we're connected via v4l2, then there should be a cleanup

	 * of the device from userspace either via UVC_EVENT_DISCONNECT or

drivers/usb/gadget/function/uvc.h

+1 −0
Original line number Diff line number Diff line
@@ -88,6 +88,7 @@ struct uvc_video { 
	struct usb_ep *ep;



	struct work_struct pump;

	struct workqueue_struct *async_wq;



	/* Frame parameters */

	u8 bpp;

drivers/usb/gadget/function/uvc_v4l2.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

}

drivers/usb/gadget/function/uvc_video.c

+7 −2
Original line number Diff line number Diff line
@@ -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
@@ -485,7 +485,7 @@ 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;

}
@@ -499,6 +499,11 @@ 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("uvcgadget", WQ_UNBOUND | WQ_HIGHPRI, 0);

	if (!video->async_wq)

		return -EINVAL;



	video->uvc = uvc;

	video->fcc = V4L2_PIX_FMT_YUYV;

	video->bpp = 16;