On Tue, Oct 11, 2022 at 10:57:07PM +0200, Michael Grzeschik wrote:
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@xxxxxxxxxxxxxx>
---
drivers/usb/gadget/function/uvc_video.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c
index bb037fcc90e69e..5081eb3bc5484c 100644
--- a/drivers/usb/gadget/function/uvc_video.c
+++ b/drivers/usb/gadget/function/uvc_video.c
@@ -448,6 +448,9 @@ 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;
@@ -479,9 +482,11 @@ 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)) ?
I also came up with the following Idea: - !(gadget->speed <= USB_SPEED_HIGH)) ? + video->req_size > 4096) ? Would this threshold of 4096 make sense? What should be preferred?
uvc_video_encode_isoc_sg : uvc_video_encode_isoc; + } video->req_int_count = 0; -- 2.30.2
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