Commit 19905240 authored by Michael Grzeschik's avatar Michael Grzeschik Committed by Greg Kroah-Hartman
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usb: gadget: uvc: limit isoc_sg to super speed gadgets 



The overhead of preparing sg data is high for transfers with limited
payload. When transferring isoc over high-speed usb the maximum payload
is rather small which is a good argument no to use sg. This patch is
changing the uvc_video_encode_isoc_sg encode function only to be used
for super speed gadgets.

Signed-off-by: default avatarMichael Grzeschik <m.grzeschik@pengutronix.de>
Cc: stable <stable@kernel.org>
Link: https://lore.kernel.org/r/20221017221141.3134818-1-m.grzeschik@pengutronix.de


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fb8f60dd

drivers/usb/gadget/function/uvc_queue.c

+3 −6
Original line number Diff line number Diff line
@@ -84,12 +84,9 @@ static int uvc_buffer_prepare(struct vb2_buffer *vb) 
		return -ENODEV;



	buf->state = UVC_BUF_STATE_QUEUED;

	if (queue->use_sg) {

	buf->sgt = vb2_dma_sg_plane_desc(vb, 0);

	buf->sg = buf->sgt->sgl;

	} else {

	buf->mem = vb2_plane_vaddr(vb, 0);

	}

	buf->length = vb2_plane_size(vb, 0);

	if (vb->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)

		buf->bytesused = 0;

drivers/usb/gadget/function/uvc_video.c

+7 −2
Original line number Diff line number Diff line
@@ -459,6 +459,9 @@ static void uvcg_video_pump(struct work_struct *work) 
 */

int uvcg_video_enable(struct uvc_video *video, int enable)

{

	struct uvc_device *uvc = video->uvc;

	struct usb_composite_dev *cdev = uvc->func.config->cdev;

	struct usb_gadget *gadget = cdev->gadget;

	unsigned int i;

	int ret;
@@ -490,9 +493,11 @@ int uvcg_video_enable(struct uvc_video *video, int enable) 
	if (video->max_payload_size) {

		video->encode = uvc_video_encode_bulk;

		video->payload_size = 0;

	} else

		video->encode = video->queue.use_sg ?

	} else {

		video->encode = (video->queue.use_sg &&

				 !(gadget->speed <= USB_SPEED_HIGH)) ?

			uvc_video_encode_isoc_sg : uvc_video_encode_isoc;

	}



	video->req_int_count = 0;