On Tue, Aug 13, 2024 at 12:41:10PM +0300, Laurent Pinchart wrote:
On Tue, Aug 13, 2024 at 11:09:30AM +0200, Michael Grzeschik wrote:The uvc gadget driver is calculating the req_size on every video_enable/alloc_request and is based on the fixed configfs parameters maxpacket, maxburst and mult. As those parameters can not be changed once the gadget is started and the same calculation is done already early on the vb2_streamon/queue_setup path its save to remove one extra calculation and reuse the calculation from uvc_queue_setup for the allocation step.Avoiding double calculations is good, but then don't compute the value in uvc_queue_setup(). That will also be called multiple times, and its timing will be controlled by userspace. Move it to a better location.
I think I was unclear regarding the avoidance of double calculations. Actually this is the right place to calculate this, since the resulting req_size will be dependent on the expected imagesize and the frameduration, we have to calculate it in every queue_setup. Since this patch is an preperation for the next change, I will leave the codebase as is but will add the details in the patch description. Michael
Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx> --- v3 -> v4: - v2 -> v3: - v1 -> v2: - --- drivers/usb/gadget/function/uvc_queue.c | 2 ++ drivers/usb/gadget/function/uvc_video.c | 15 ++------------- 2 files changed, 4 insertions(+), 13 deletions(-) diff --git a/drivers/usb/gadget/function/uvc_queue.c b/drivers/usb/gadget/function/uvc_queue.c index 7995dd3fef184..2414d78b031f4 100644 --- a/drivers/usb/gadget/function/uvc_queue.c +++ b/drivers/usb/gadget/function/uvc_queue.c @@ -63,6 +63,8 @@ static int uvc_queue_setup(struct vb2_queue *vq, */ nreq = DIV_ROUND_UP(DIV_ROUND_UP(sizes[0], 2), req_size); nreq = clamp(nreq, 4U, 64U); + + video->req_size = req_size; video->uvc_num_requests = nreq; return 0; diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c index 259920ae36843..a6786beef91ad 100644 --- a/drivers/usb/gadget/function/uvc_video.c +++ b/drivers/usb/gadget/function/uvc_video.c @@ -480,7 +480,6 @@ uvc_video_free_requests(struct uvc_video *video) INIT_LIST_HEAD(&video->ureqs); INIT_LIST_HEAD(&video->req_free); INIT_LIST_HEAD(&video->req_ready); - video->req_size = 0; return 0; } @@ -488,16 +487,9 @@ static int uvc_video_alloc_requests(struct uvc_video *video) { struct uvc_request *ureq; - unsigned int req_size; unsigned int i; int ret = -ENOMEM; - BUG_ON(video->req_size); - - req_size = video->ep->maxpacket - * max_t(unsigned int, video->ep->maxburst, 1) - * (video->ep->mult); - for (i = 0; i < video->uvc_num_requests; i++) { ureq = kzalloc(sizeof(struct uvc_request), GFP_KERNEL); if (ureq == NULL) @@ -507,7 +499,7 @@ uvc_video_alloc_requests(struct uvc_video *video) list_add_tail(&ureq->list, &video->ureqs); - ureq->req_buffer = kmalloc(req_size, GFP_KERNEL); + ureq->req_buffer = kmalloc(video->req_size, GFP_KERNEL); if (ureq->req_buffer == NULL) goto error; @@ -525,12 +517,10 @@ uvc_video_alloc_requests(struct uvc_video *video) list_add_tail(&ureq->req->list, &video->req_free); /* req_size/PAGE_SIZE + 1 for overruns and + 1 for header */ sg_alloc_table(&ureq->sgt, - DIV_ROUND_UP(req_size - UVCG_REQUEST_HEADER_LEN, + DIV_ROUND_UP(video->req_size - UVCG_REQUEST_HEADER_LEN, PAGE_SIZE) + 2, GFP_KERNEL); } - video->req_size = req_size; - return 0; error: @@ -663,7 +653,6 @@ uvcg_video_disable(struct uvc_video *video) INIT_LIST_HEAD(&video->ureqs); INIT_LIST_HEAD(&video->req_free); INIT_LIST_HEAD(&video->req_ready); - video->req_size = 0; spin_unlock_irqrestore(&video->req_lock, flags); /*-- Regards, Laurent Pinchart
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