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usb: gadget: uvc: limit isoc_sg to super speed gadgets

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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: Michael 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Grzeschik 2022-10-18 00:11:41 +02:00 committed by Greg Kroah-Hartman
parent fb8f60dd1b
commit 19905240ae
2 changed files with 10 additions and 8 deletions
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9
drivers/usb/gadget/function/uvc_queue.c
View File

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

9
drivers/usb/gadget/function/uvc_video.c
View File

@ -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;