On Wed, Jun 08, 2022 at 09:41:30PM +0300, Laurent Pinchart wrote:
Hi Michael, Thank you for the patch. On Wed, Jun 08, 2022 at 01:03:38PM +0200, Michael Grzeschik wrote: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 d3feeeb50841b8..dcc5f057810973 100644 --- a/drivers/usb/gadget/function/f_uvc.c +++ b/drivers/usb/gadget/function/f_uvc.c @@ -891,10 +891,14 @@ 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 * though the video device removal uevent. Allow some time for the diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h index 58e383afdd4406..1a31e6c6a5ffb8 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 fd8f73bb726dd1..fddc392b8ab95d 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);Let's call it "uvcgadget" (or "uvc gadget", "uvc-gadget", ...) as "uvcvideo" refers to the host side driver.
Good Idea. I will fix this.
I'm still a bit worried about WQ_UNBOUND and the risk of running work items in parallel on different CPUs. uvcg_video_pump() looks mostly safe, as it protects video->req_free with a spinlock, and the buffer queue with another spinlock. The req_int_count increment at the end of the loop would be unsafe though.
I didn't think about that. I will have to check for that.
Could we get to the bottom of this and find out whether or not the work items can be executed in parallel ?
Do you have an Idea to check for that?
+ if (!video->async_wq) + return -EINVAL; + video->uvc = uvc; video->fcc = V4L2_PIX_FMT_YUYV; video->bpp = 16;-- Regards, Laurent Pinchart
-- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
Attachment:
signature.asc
Description: PGP signature
