This is a note to let you know that I've just added the patch titled
usb: gadget: uvc: limit isoc_sg to super speed gadgets
to the 6.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-gadget-uvc-limit-isoc_sg-to-super-speed-gadgets.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 19905240aef0181d1e6944070eb85fce75f75bcd Mon Sep 17 00:00:00 2001
From: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
Date: Tue, 18 Oct 2022 00:11:41 +0200
Subject: usb: gadget: uvc: limit isoc_sg to super speed gadgets
From: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
commit 19905240aef0181d1e6944070eb85fce75f75bcd upstream.
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>
Cc: stable <stable@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20221017221141.3134818-1-m.grzeschik@xxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/gadget/function/uvc_queue.c | 9 +++------
drivers/usb/gadget/function/uvc_video.c | 9 +++++++--
2 files changed, 10 insertions(+), 8 deletions(-)
--- a/drivers/usb/gadget/function/uvc_queue.c
+++ b/drivers/usb/gadget/function/uvc_queue.c
@@ -84,12 +84,9 @@ static int uvc_buffer_prepare(struct vb2
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;
--- 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_
*/
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 *
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;
Patches currently in stable-queue which might be from m.grzeschik@xxxxxxxxxxxxxx are
queue-6.0/revert-usb-gadget-uvc-limit-isoc_sg-to-super-speed-gadgets.patch
queue-6.0/usb-gadget-uvc-limit-isoc_sg-to-super-speed-gadgets.patch
