This patch adds the support in UVC webcam gadget to allocate UVC header and
payload as Scatter-Gather elements which can be used on a SG-capable UDC
controller.
A module parameter has been introduced for the same. One can set the
module parameter 'sg_mode' to 1 to turn on this feature (by default this
feature is turned-off).
This ensures that we don't require a memcpy from CPU side to append UVC
header in front of the UVC payload atleast for SG capable UDC contollers.
Signed-off-by: Bhupesh Sharma <bhupesh.sha...@st.com>
---
Note that to ease review and integration of this patch, I have rebased it
on the following patch already circulated for review last week:
[PATCH 1/1] usb: gadget/uvc: Add support for Bulk endpoint to be used as
Video Streaming ep
http://www.mail-archive.com/linux-usb@vger.kernel.org/msg19546.html
The above patch was rebased on Laurent's UVC gadget git tree available here
(head uvc-gadget):
git://linuxtv.org/pinchartl/uvcvideo.git
This will allow the patches to be pulled into Felipe's repo in one go
after review and any subsequent rework (if required).
drivers/usb/gadget/f_uvc.c | 8 +++
drivers/usb/gadget/uvc.h | 2 +
drivers/usb/gadget/uvc_video.c | 113 +++++++++++++++++++++++++++++++++++-----
3 files changed, 109 insertions(+), 14 deletions(-)
diff --git a/drivers/usb/gadget/f_uvc.c b/drivers/usb/gadget/f_uvc.c
index e5953eb..ccf0253 100644
--- a/drivers/usb/gadget/f_uvc.c
+++ b/drivers/usb/gadget/f_uvc.c
@@ -50,6 +50,11 @@ module_param(bulk_streaming_ep, bool, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(bulk_streaming_ep, "0 (Use ISOC video streaming ep) / "
"1 (Use BULK video streaming ep)");
+static bool sg_mode;
+module_param(sg_mode, bool, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(sg_mode, "0 (Don't use SG feature) / "
+ "1 (Use scatterlist for SG-capable controllers)");
+
/* --------------------------------------------------------------------------
* Function descriptors
*/
@@ -888,6 +893,9 @@ uvc_function_bind(struct usb_configuration *c, struct
usb_function *f)
uvc->control_req->complete = uvc_function_ep0_complete;
uvc->control_req->context = uvc;
+ /* Use SG mode ? */
+ uvc->video.sg_mode = sg_mode;
+
/* Avoid letting this gadget enumerate until the userspace server is
* active.
*/
diff --git a/drivers/usb/gadget/uvc.h b/drivers/usb/gadget/uvc.h
index 8756853..3a54510 100644
--- a/drivers/usb/gadget/uvc.h
+++ b/drivers/usb/gadget/uvc.h
@@ -122,6 +122,7 @@ struct uvc_video
struct usb_request *req[UVC_NUM_REQUESTS];
__u8 *req_buffer[UVC_NUM_REQUESTS];
struct list_head req_free;
+ unsigned char *header_buf;
spinlock_t req_lock;
void (*encode) (struct usb_request *req, struct uvc_video *video,
@@ -135,6 +136,7 @@ struct uvc_video
unsigned int fid;
bool bulk_streaming_ep;
+ bool sg_mode;
};
enum uvc_state
diff --git a/drivers/usb/gadget/uvc_video.c b/drivers/usb/gadget/uvc_video.c
index 87ac526..5f92f93 100644
--- a/drivers/usb/gadget/uvc_video.c
+++ b/drivers/usb/gadget/uvc_video.c
@@ -39,6 +39,25 @@ uvc_video_encode_header(struct uvc_video *video, struct
uvc_buffer *buf,
}
static int
+uvc_video_encode_header_sg(struct uvc_video *video, struct uvc_buffer *buf,
+ int len)
+{
+ unsigned char *data = video->header_buf;
+
+ *data++ = 2;
+ *data = UVC_STREAM_EOH | video->fid;
+
+ if (!video->bulk_streaming_ep) {
+ if (buf->bytesused - video->queue.buf_used <= len - 2)
+ *data |= UVC_STREAM_EOF;
+ } else {
+ *data |= UVC_STREAM_EOF;
+ }
+
+ return 2;
+}
+
+static int
uvc_video_encode_data(struct uvc_video *video, struct uvc_buffer *buf,
u8 *data, int len)
{
@@ -56,25 +75,57 @@ uvc_video_encode_data(struct uvc_video *video, struct
uvc_buffer *buf,
return nbytes;
}
+static int
+uvc_video_encode_data_sg(struct uvc_video *video, struct uvc_buffer *buf,
+ struct scatterlist *sg, int len)
+{
+ struct uvc_video_queue *queue = &video->queue;
+ unsigned int nbytes;
+
+ /* Pass pointer of video frame data to the USB req->sg. */
+ nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
+
+ sg_set_buf(sg, (void *)(buf->mem + queue->buf_used), len);
+ queue->buf_used += nbytes;
+
+ return nbytes;
+}
+
static void
uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video,
struct uvc_buffer *buf)
{
- void *mem = req->buf;
+ struct scatterlist *sg = NULL;
+ void *mem = NULL;
int len = video->req_size;
int ret;
/* Add a header at the beginning of the payload. */
+ if (!video->sg_mode)
+ mem = req->buf;
+ else
+ sg = req->sg;
+
if (video->payload_size == 0) {
- ret = uvc_video_encode_header(video, buf, mem, len);
+ if (!video->sg_mode) {
+ ret = uvc_video_encode_header(video, buf, mem, len);
+ mem += ret;
+ } else {
+ ret = uvc_video_encode_header_sg(video, buf, len);
+ }
+
video->payload_size += ret;
- mem += ret;
len -= ret;
}
/* Process video data. */
len = min((int)(video->max_payload_size - video->payload_size), len);
- ret = uvc_video_encode_data(video, buf, mem, len);
+ if (!video->sg_mode) {
+ ret = uvc_video_encode_data(video, buf, mem, len);
+ } else {
+ sg++;
+ ret = uvc_video_encode_data_sg(video, buf, sg, len);
+ }
video->payload_size += ret;
len -= ret;
@@ -100,17 +151,29 @@ static void
uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
struct uvc_buffer *buf)
{
+ struct scatterlist *sg = NULL;
void *mem = req->buf;
int len = video->req_size;
int ret;
/* Add the header. */
- ret = uvc_video_encode_header(video, buf, mem, len);
+ if (!video->sg_mode)
+ ret = uvc_video_encode_header(video, buf, mem, len);
+ else
+ ret = uvc_video_encode_header_sg(video, buf, len);
+
mem += ret;
len -= ret;
/* Process video data. */
- ret = uvc_video_encode_data(video, buf, mem, len);
+ if (!video->sg_mode) {
+ ret = uvc_video_encode_data(video, buf, mem, len);
+ } else {
+ sg = req->sg;
+ sg++;
+ ret = uvc_video_encode_data_sg(video, buf, sg, len);
+ }
+
len -= ret;
req->length = video->req_size - len;
@@ -212,13 +275,19 @@ uvc_video_free_requests(struct uvc_video *video)
{
unsigned int i;
+ if (video->sg_mode && video->header_buf)
+ kfree(video->header_buf);
+
for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
+ if (video->sg_mode && video->req[i]->sg)
+ kfree(video->req[i]->sg);
+
if (video->req[i]) {
usb_ep_free_request(video->ep, video->req[i]);
video->req[i] = NULL;
}
- if (video->req_buffer[i]) {
+ if (!video->sg_mode && video->req_buffer[i]) {
kfree(video->req_buffer[i]);
video->req_buffer[i] = NULL;
}
@@ -243,19 +312,35 @@ uvc_video_alloc_requests(struct uvc_video *video)
* max_t(unsigned int, video->ep->maxburst, 1)
* (video->ep->mult + 1);
else
- req_size = video->ep->maxpacket
- * max_t(unsigned int, video->ep->maxburst, 1);
+ req_size = max_t(unsigned int, video->imagesize,
+ video->ep->maxpacket
+ * max_t(unsigned int, video->ep->maxburst, 1));
- for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
- video->req_buffer[i] = kmalloc(req_size, GFP_KERNEL);
- if (video->req_buffer[i] == NULL)
- goto error;
+ /* Allocate a UVC header here itself for SG mode. */
+ if (video->sg_mode)
+ video->header_buf = kmalloc(2 * sizeof(video->header_buf),
+ GFP_DMA);
+ for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
if (video->req[i] == NULL)
goto error;
- video->req[i]->buf = video->req_buffer[i];
+ if (!video->sg_mode) {
+ video->req_buffer[i] = kmalloc(req_size, GFP_KERNEL);
+ if (video->req_buffer[i] == NULL)
+ goto error;
+
+ video->req[i]->buf = video->req_buffer[i];
+ } else {
+ video->req[i]->sg =
+ kmalloc(2 * sizeof(video->req[i]->sg), GFP_DMA);
+ video->req[i]->num_sgs = 2;
+ sg_init_table(video->req[i]->sg, 2);
+ sg_set_buf(video->req[i]->sg,
+ (void *)video->header_buf, 2);
+ }
+
video->req[i]->length = 0;
video->req[i]->complete = uvc_video_complete;
video->req[i]->context = video;
--
1.7.2.2
--
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