[PATCH 5.19 662/717] usb: gadget: uvc: increase worker prio to WQ_HIGHPRI

Greg Kroah-Hartman
2022-10-22T11:17:01Z

From: Michael Grzeschik <m.grzeschik@pengutronix.de>

[ Upstream commit 9b91a65230784a9ef644b8bdbb82a79ba4ae9456 ]

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: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20220907215818.2670097-1-m.grzeschik@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 86bb0098fb66..7ec223849d94 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -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
diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h
index 58e383afdd44..1a31e6c6a5ff 100644
--- a/drivers/usb/gadget/function/uvc.h
+++ b/drivers/usb/gadget/function/uvc.h
@@ -88,6 +88,7 @@ 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 fd8f73bb726d..fddc392b8ab9 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 c00ce0e91f5d..bb037fcc90e6 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
@@ -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;
--
2.35.1