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usb: gadget: uvc: add scatter gather support

Browse Source 
This patch adds support for scatter gather transfers. If the underlying
gadgets sg_supported == true, then the videeobuf2-dma-sg is used and the
encode routine maps all scatter entries to separate scatterlists for the
usb gadget.

When streaming 1080p with request size of 1024 times 3 bytes top shows a
difference of about 6.4% CPU load applying this patch:

 PID USER      PR  NI    VIRT    RES  %CPU  %MEM     TIME+ S COMMAND

  64 root       0 -20    0.0m   0.0m   7.7   0.0   0:01.25 I [kworker/u5:0-uvcvideo]
  83 root       0 -20    0.0m   0.0m   4.5   0.0   0:03.71 I [kworker/u5:3-uvcvideo]
 307 root     -51   0    0.0m   0.0m   3.8   0.0   0:01.05 S [irq/51-dwc3]

vs.

  64 root       0 -20    0.0m   0.0m   5.8   0.0   0:01.79 I [kworker/u5:0-uvcvideo]
 306 root     -51   0    0.0m   0.0m   3.2   0.0   0:01.97 S [irq/51-dwc3]
  82 root       0 -20    0.0m   0.0m   0.6   0.0   0:01.86 I [kworker/u5:1-uvcvideo]

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20210628155311.16762-5-m.grzeschik@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Grzeschik 2021-06-28 17:53:10 +02:00 committed by Greg Kroah-Hartman
parent b9b82d3d0d
commit e81e7f9a0e
7 changed files with 108 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/usb/gadget/Kconfig
View File

@ -450,6 +450,7 @@ config USB_CONFIGFS_F_UVC
depends on USB_CONFIGFS
depends on VIDEO_V4L2
depends on VIDEO_DEV
select VIDEOBUF2_DMA_SG
select VIDEOBUF2_VMALLOC
select USB_F_UVC
help

2
drivers/usb/gadget/function/uvc.h
View File

@ -75,6 +75,8 @@ struct uvc_request {
struct usb_request *req;
u8 *req_buffer;
struct uvc_video *video;
struct sg_table sgt;
u8 header[2];
};
struct uvc_video {

22
drivers/usb/gadget/function/uvc_queue.c
View File

@ -17,6 +17,7 @@
#include <linux/wait.h>
#include <media/v4l2-common.h>
#include <media/videobuf2-dma-sg.h>
#include <media/videobuf2-vmalloc.h>
#include "uvc.h"
@ -76,7 +77,12 @@ static int uvc_buffer_prepare(struct vb2_buffer *vb)
return -ENODEV;
buf->state = UVC_BUF_STATE_QUEUED;
buf->mem = vb2_plane_vaddr(vb, 0);
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;
@ -116,9 +122,11 @@ static const struct vb2_ops uvc_queue_qops = {
.wait_finish = vb2_ops_wait_finish,
};
int uvcg_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
int uvcg_queue_init(struct uvc_video_queue *queue, struct device *dev, enum v4l2_buf_type type,
struct mutex *lock)
{
struct uvc_video *video = container_of(queue, struct uvc_video, queue);
struct usb_composite_dev *cdev = video->uvc->func.config->cdev;
int ret;
queue->queue.type = type;
@ -127,9 +135,17 @@ int uvcg_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
queue->queue.buf_struct_size = sizeof(struct uvc_buffer);
queue->queue.ops = &uvc_queue_qops;
queue->queue.lock = lock;
queue->queue.mem_ops = &vb2_vmalloc_memops;
if (cdev->gadget->sg_supported) {
queue->queue.mem_ops = &vb2_dma_sg_memops;
queue->use_sg = 1;
} else {
queue->queue.mem_ops = &vb2_vmalloc_memops;
}
queue->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC
| V4L2_BUF_FLAG_TSTAMP_SRC_EOF;
queue->queue.dev = dev;
ret = vb2_queue_init(&queue->queue);
if (ret)
return ret;

7
drivers/usb/gadget/function/uvc_queue.h
View File

@ -34,6 +34,9 @@ struct uvc_buffer {
enum uvc_buffer_state state;
void *mem;
struct sg_table *sgt;
struct scatterlist *sg;
unsigned int offset;
unsigned int length;
unsigned int bytesused;
};
@ -50,6 +53,8 @@ struct uvc_video_queue {
unsigned int buf_used;
bool use_sg;
spinlock_t irqlock; /* Protects flags and irqqueue */
struct list_head irqqueue;
};
@ -59,7 +64,7 @@ static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
return vb2_is_streaming(&queue->queue);
}
int uvcg_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
int uvcg_queue_init(struct uvc_video_queue *queue, struct device *dev, enum v4l2_buf_type type,
struct mutex *lock);
void uvcg_free_buffers(struct uvc_video_queue *queue);

82
drivers/usb/gadget/function/uvc_video.c
View File

@ -27,10 +27,10 @@ static int
uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
u8 *data, int len)
{
data[0] = 2;
data[0] = UVCG_REQUEST_HEADER_LEN;
data[1] = UVC_STREAM_EOH | video->fid;
if (buf->bytesused - video->queue.buf_used <= len - 2)
if (buf->bytesused - video->queue.buf_used <= len - UVCG_REQUEST_HEADER_LEN)
data[1] |= UVC_STREAM_EOF;
return 2;
@ -94,6 +94,71 @@ uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video,
video->payload_size = 0;
}
static void
uvc_video_encode_isoc_sg(struct usb_request *req, struct uvc_video *video,
struct uvc_buffer *buf)
{
unsigned int pending = buf->bytesused - video->queue.buf_used;
struct uvc_request *ureq = req->context;
struct scatterlist *sg, *iter;
unsigned int len = video->req_size;
unsigned int sg_left, part = 0;
unsigned int i;
int ret;
sg = ureq->sgt.sgl;
sg_init_table(sg, ureq->sgt.nents);
/* Init the header. */
ret = uvc_video_encode_header(video, buf, ureq->header,
video->req_size);
sg_set_buf(sg, ureq->header, UVCG_REQUEST_HEADER_LEN);
len -= ret;
if (pending <= len)
len = pending;
req->length = (len == pending) ?
len + UVCG_REQUEST_HEADER_LEN : video->req_size;
/* Init the pending sgs with payload */
sg = sg_next(sg);
for_each_sg(sg, iter, ureq->sgt.nents - 1, i) {
if (!len || !buf->sg)
break;
sg_left = sg_dma_len(buf->sg) - buf->offset;
part = min_t(unsigned int, len, sg_left);
sg_set_page(iter, sg_page(buf->sg), part, buf->offset);
if (part == sg_left) {
buf->offset = 0;
buf->sg = sg_next(buf->sg);
} else {
buf->offset += part;
}
len -= part;
}
/* Assign the video data with header. */
req->buf = NULL;
req->sg = ureq->sgt.sgl;
req->num_sgs = i + 1;
req->length -= len;
video->queue.buf_used += req->length - UVCG_REQUEST_HEADER_LEN;
if (buf->bytesused == video->queue.buf_used || !buf->sg) {
video->queue.buf_used = 0;
buf->state = UVC_BUF_STATE_DONE;
buf->offset = 0;
uvcg_queue_next_buffer(&video->queue, buf);
video->fid ^= UVC_STREAM_FID;
}
}
static void
uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
struct uvc_buffer *buf)
@ -180,6 +245,8 @@ uvc_video_free_requests(struct uvc_video *video)
if (video->ureq) {
for (i = 0; i < video->uvc_num_requests; ++i) {
sg_free_table(&video->ureq[i].sgt);
if (video->ureq[i].req) {
usb_ep_free_request(video->ep, video->ureq[i].req);
video->ureq[i].req = NULL;
@ -233,6 +300,10 @@ uvc_video_alloc_requests(struct uvc_video *video)
video->ureq[i].video = video;
list_add_tail(&video->ureq[i].req->list, &video->req_free);
/* req_size/PAGE_SIZE + 1 for overruns and + 1 for header */
sg_alloc_table(&video->ureq[i].sgt,
DIV_ROUND_UP(req_size - 2, PAGE_SIZE) + 2,
GFP_KERNEL);
}
video->req_size = req_size;
@ -342,7 +413,8 @@ int uvcg_video_enable(struct uvc_video *video, int enable)
video->encode = uvc_video_encode_bulk;
video->payload_size = 0;
} else
video->encode = uvc_video_encode_isoc;
video->encode = video->queue.use_sg ?
uvc_video_encode_isoc_sg : uvc_video_encode_isoc;
schedule_work(&video->pump);
@ -366,8 +438,8 @@ int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc)
video->imagesize = 320 * 240 * 2;
/* Initialize the video buffers queue. */
uvcg_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT,
&video->mutex);
uvcg_queue_init(&video->queue, uvc->v4l2_dev.dev->parent,
V4L2_BUF_TYPE_VIDEO_OUTPUT, &video->mutex);
return 0;
}

2
drivers/usb/gadget/function/uvc_video.h
View File

@ -12,6 +12,8 @@
#ifndef __UVC_VIDEO_H__
#define __UVC_VIDEO_H__
#define UVCG_REQUEST_HEADER_LEN 2
struct uvc_video;
int uvcg_video_enable(struct uvc_video *video, int enable);

1
drivers/usb/gadget/legacy/Kconfig
View File

@ -502,6 +502,7 @@ config USB_G_WEBCAM
tristate "USB Webcam Gadget"
depends on VIDEO_V4L2
select USB_LIBCOMPOSITE
select VIDEOBUF2_DMA_SG
select VIDEOBUF2_VMALLOC
select USB_F_UVC
help