Re: [PATCH v8 4/4] usb: gadget: uvc: add format/frame handling code

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Hi Michael,

Thank you for the patch.

On Wed, Sep 07, 2022 at 04:02:54PM +0200, Michael Grzeschik wrote:
> The Hostside format selection is currently only done in userspace, as
> the events for SET_CUR and GET_CUR are always moved to the application
> layer. Since the v4l2 device parses the configfs data, the format
> negotiation can be done in the kernel. This patch adds the functions to
> set the current configuration while continuing to forward all unknown
> events to the userspace level.

Why do you think this is better done in kernel space, given that
userspace has to process the event anyway ? It's more complexity in the
kernel side, for little added value as far as I can see. It will also
make it more difficult to handle different UVC versions (in particular
UVC 1.5). I'd rather not go in this direction if there's no clear
benefit.

> Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
> 
> ---
> v1 -> v2:
>    - fixed the commit message
>    - changed pr_debug to pr_err in events_process_data
>    - aligned many indentations
>    - simplified uvc_events_process_data
>    - fixed uvc_fill_streaming_control calls in uvcg_video_init
>    - added setup_subscribed to decide if userspace takes over on EOPNOTSUPP
>    - added data_subscribed to decide if userspace takes over on EOPNOTSUPP
>    - removed duplicate send_response
>    - wrting fmt and frm in full
> v2 -> v3:
>    - added find_format_index to set the right probe
> v3 -> v4:
>    - add function find_ival_index and use for cur_ival
>    - fix swapped frame and format in uvc_events_process_data on uvc_fill_streaming_control
>    - set proper resp.length on ep0 complete
>    - dropped setting cur_probe on set_format since function was removed
>    - added locking around getting correspondent cur_{frame,format,ival}
> v4 -> v5:
>    - fixed sparse errors reported by kernel test robot
> v5 -> v6:
>    - fixed the handling in uvc_function_ep0_complete after events_process_data
> v6 -> v7:
>    - set dwMaxPayloadTransferSize unconditionally from streaming_maxpacket
>    - fixed check for interface with masking for 0xff
> v7 -> v8:
>    -
> 
>  drivers/usb/gadget/function/f_uvc.c     | 237 +++++++++++++++++++++++-
>  drivers/usb/gadget/function/uvc.h       |  19 ++
>  drivers/usb/gadget/function/uvc_v4l2.c  |  66 ++++++-
>  drivers/usb/gadget/function/uvc_video.c |  12 +-
>  4 files changed, 322 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
> index a8dcf5f01f16de..fc3fabc47018cd 100644
> --- a/drivers/usb/gadget/function/f_uvc.c
> +++ b/drivers/usb/gadget/function/f_uvc.c
> @@ -16,7 +16,6 @@
>  #include <linux/string.h>
>  #include <linux/usb/ch9.h>
>  #include <linux/usb/gadget.h>
> -#include <linux/usb/g_uvc.h>
>  #include <linux/usb/video.h>
>  #include <linux/vmalloc.h>
>  #include <linux/wait.h>
> @@ -204,21 +203,228 @@ static const struct usb_descriptor_header * const uvc_ss_streaming[] = {
>   * Control requests
>   */
>  
> +void uvc_fill_streaming_control(struct uvc_device *uvc,
> +			   struct uvc_streaming_control *ctrl,
> +			   int iframe, int iformat, unsigned int ival)
> +{
> +	struct f_uvc_opts *opts;
> +	struct uvcg_format *uformat;
> +	struct uvcg_frame *uframe;
> +
> +	/* Restrict the iformat, iframe and ival to valid values. Negative
> +	 * values for ifrmat and iframe will result in the maximum valid value
> +	 * being selected
> +	 */
> +	iformat = clamp((unsigned int)iformat, 1U,
> +			(unsigned int)uvc->header->num_fmt);
> +	uformat = find_format_by_index(uvc, iformat);
> +	if (!uformat)
> +		return;
> +
> +	iframe = clamp((unsigned int)iframe, 1U,
> +		       (unsigned int)uformat->num_frames);
> +	uframe = find_frame_by_index(uvc, uformat, iframe);
> +	if (!uframe)
> +		return;
> +
> +	ival = clamp((unsigned int)ival, 1U,
> +		     (unsigned int)uframe->frame.b_frame_interval_type);
> +	if (!uframe->dw_frame_interval[ival - 1])
> +		return;
> +
> +	opts = fi_to_f_uvc_opts(uvc->func.fi);
> +
> +	memset(ctrl, 0, sizeof(*ctrl));
> +
> +	ctrl->bmHint = 1;
> +	ctrl->bFormatIndex = iformat;
> +	ctrl->bFrameIndex = iframe;
> +	ctrl->dwFrameInterval = uframe->dw_frame_interval[ival - 1];
> +	ctrl->dwMaxVideoFrameSize =
> +		uframe->frame.dw_max_video_frame_buffer_size;
> +
> +	ctrl->dwMaxPayloadTransferSize = opts->streaming_maxpacket;
> +	ctrl->bmFramingInfo = 3;
> +	ctrl->bPreferedVersion = 1;
> +	ctrl->bMaxVersion = 1;
> +}
> +
> +static int uvc_events_process_data(struct uvc_device *uvc,
> +				   struct usb_request *req)
> +{
> +	struct uvc_video *video = &uvc->video;
> +	struct uvc_streaming_control *target;
> +	struct uvc_streaming_control *ctrl;
> +	struct uvcg_frame *uframe;
> +	struct uvcg_format *uformat;
> +
> +	switch (video->control) {
> +	case UVC_VS_PROBE_CONTROL:
> +		pr_debug("setting probe control, length = %d\n", req->actual);
> +		target = &video->probe;
> +		break;
> +
> +	case UVC_VS_COMMIT_CONTROL:
> +		pr_debug("setting commit control, length = %d\n", req->actual);
> +		target = &video->commit;
> +		break;
> +
> +	default:
> +		pr_err("setting unknown control, length = %d\n", req->actual);
> +		return -EOPNOTSUPP;
> +	}
> +
> +	ctrl = (struct uvc_streaming_control *)req->buf;
> +
> +	uvc_fill_streaming_control(uvc, target, ctrl->bFrameIndex,
> +			   ctrl->bFormatIndex, ctrl->dwFrameInterval);
> +
> +	if (video->control == UVC_VS_COMMIT_CONTROL) {
> +		uformat = find_format_by_index(uvc, target->bFormatIndex);
> +		if (!uformat)
> +			return -EINVAL;
> +
> +		uframe = find_frame_by_index(uvc, uformat, ctrl->bFrameIndex);
> +		if (!uframe)
> +			return -EINVAL;
> +
> +		spin_lock(&video->frame_lock);
> +
> +		video->cur_frame = uframe;
> +		video->cur_format = uformat;
> +		video->cur_ival = find_ival_index(uframe, ctrl->dwFrameInterval);
> +
> +		spin_unlock(&video->frame_lock);
> +	}
> +
> +	return 0;
> +}
> +
> +static void
> +uvc_events_process_streaming(struct uvc_device *uvc, uint8_t req, uint8_t cs,
> +			     struct uvc_request_data *resp)
> +{
> +	struct uvc_streaming_control *ctrl;
> +
> +	pr_debug("streaming request (req %02x cs %02x)\n", req, cs);
> +
> +	if (cs != UVC_VS_PROBE_CONTROL && cs != UVC_VS_COMMIT_CONTROL)
> +		return;
> +
> +	ctrl = (struct uvc_streaming_control *)&resp->data;
> +	resp->length = sizeof(*ctrl);
> +
> +	switch (req) {
> +	case UVC_SET_CUR:
> +		uvc->video.control = cs;
> +		resp->length = 34;
> +		break;
> +
> +	case UVC_GET_CUR:
> +		if (cs == UVC_VS_PROBE_CONTROL)
> +			memcpy(ctrl, &uvc->video.probe, sizeof(*ctrl));
> +		else
> +			memcpy(ctrl, &uvc->video.commit, sizeof(*ctrl));
> +		break;
> +
> +	case UVC_GET_MIN:
> +	case UVC_GET_MAX:
> +	case UVC_GET_DEF:
> +		if (req == UVC_GET_MAX)
> +			uvc_fill_streaming_control(uvc, ctrl, -1, -1, UINT_MAX);
> +		else
> +			uvc_fill_streaming_control(uvc, ctrl, 1, 1, 0);
> +		break;
> +
> +	case UVC_GET_RES:
> +		memset(ctrl, 0, sizeof(*ctrl));
> +		break;
> +
> +	case UVC_GET_LEN:
> +		resp->data[0] = 0x00;
> +		resp->data[1] = 0x22;
> +		resp->length = 2;
> +		break;
> +
> +	case UVC_GET_INFO:
> +		resp->data[0] = 0x03;
> +		resp->length = 1;
> +		break;
> +	}
> +}
> +
> +static int
> +uvc_events_process_class(struct uvc_device *uvc,
> +			 const struct usb_ctrlrequest *ctrl,
> +			 struct uvc_request_data *resp)
> +{
> +	unsigned int interface = le16_to_cpu(ctrl->wIndex) & 0xff;
> +
> +	if ((ctrl->bRequestType & USB_RECIP_MASK) != USB_RECIP_INTERFACE)
> +		return -EINVAL;
> +
> +	if (interface == uvc->control_intf)
> +		return -EOPNOTSUPP;
> +	else if (interface == uvc->streaming_intf)
> +		uvc_events_process_streaming(uvc, ctrl->bRequest,
> +					     le16_to_cpu(ctrl->wValue) >> 8,
> +					     resp);
> +
> +	return 0;
> +}
> +
> +static int
> +uvc_events_process_setup(struct uvc_device *uvc,
> +			 const struct usb_ctrlrequest *ctrl,
> +			 struct uvc_request_data *resp)
> +{
> +	uvc->video.control = 0;
> +
> +	pr_debug("bRequestType %02x bRequest %02x wValue %04x wIndex %04x wLength %04x\n",
> +		ctrl->bRequestType, ctrl->bRequest, ctrl->wValue,
> +		ctrl->wIndex, ctrl->wLength);
> +
> +	switch (ctrl->bRequestType & USB_TYPE_MASK) {
> +	case USB_TYPE_STANDARD:
> +		return -EOPNOTSUPP;
> +
> +	case USB_TYPE_CLASS:
> +		return uvc_events_process_class(uvc, ctrl, resp);
> +
> +	default:
> +		break;
> +	}
> +
> +	return 0;
> +}
> +
>  static void
>  uvc_function_ep0_complete(struct usb_ep *ep, struct usb_request *req)
>  {
>  	struct uvc_device *uvc = req->context;
>  	struct v4l2_event v4l2_event;
>  	struct uvc_event *uvc_event = (void *)&v4l2_event.u.data;
> +	int ret;
>  
>  	if (uvc->event_setup_out) {
>  		uvc->event_setup_out = 0;
>  
> -		memset(&v4l2_event, 0, sizeof(v4l2_event));
> -		v4l2_event.type = UVC_EVENT_DATA;
> -		uvc_event->data.length = req->actual;
> -		memcpy(&uvc_event->data.data, req->buf, req->actual);
> -		v4l2_event_queue(&uvc->vdev, &v4l2_event);
> +		ret = uvc_events_process_data(uvc, req);
> +		/* If we have a real error on process */
> +		if (ret == -EINVAL) {
> +			struct uvc_request_data resp;
> +
> +			memset(&resp, 0, sizeof(resp));
> +			resp.length = -EL2HLT;
> +
> +			uvc_send_response(uvc, &resp);
> +		} else if (ret == -EOPNOTSUPP && uvc->data_subscribed) {
> +			memset(&v4l2_event, 0, sizeof(v4l2_event));
> +			v4l2_event.type = UVC_EVENT_DATA;
> +			uvc_event->data.length = req->actual;
> +			memcpy(&uvc_event->data.data, req->buf, req->actual);
> +			v4l2_event_queue(&uvc->vdev, &v4l2_event);
> +		}
>  	}
>  }
>  
> @@ -228,6 +434,8 @@ uvc_function_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
>  	struct uvc_device *uvc = to_uvc(f);
>  	struct v4l2_event v4l2_event;
>  	struct uvc_event *uvc_event = (void *)&v4l2_event.u.data;
> +	struct uvc_request_data resp;
> +	int ret = 0;
>  
>  	if ((ctrl->bRequestType & USB_TYPE_MASK) != USB_TYPE_CLASS) {
>  		uvcg_info(f, "invalid request type\n");
> @@ -245,6 +453,23 @@ uvc_function_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
>  	uvc->event_setup_out = !(ctrl->bRequestType & USB_DIR_IN);
>  	uvc->event_length = le16_to_cpu(ctrl->wLength);
>  
> +	memset(&resp, 0, sizeof(resp));
> +	resp.length = -EL2HLT;
> +
> +	ret = uvc_events_process_setup(uvc, ctrl, &resp);
> +	/* If we have no error on process */
> +	if (!ret)
> +		return uvc_send_response(uvc, &resp);
> +
> +	/* If we have a real error on process */
> +	if (ret != -EOPNOTSUPP)
> +		return ret;
> +
> +	/* If we have -EOPNOTSUPP */
> +	if (!uvc->setup_subscribed)
> +		return uvc_send_response(uvc, &resp);
> +
> +	/* If we have setup subscribed */
>  	memset(&v4l2_event, 0, sizeof(v4l2_event));
>  	v4l2_event.type = UVC_EVENT_SETUP;
>  	memcpy(&uvc_event->req, ctrl, sizeof(uvc_event->req));
> diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h
> index 8a71d0c4abbcd5..cdfd46f3a2861c 100644
> --- a/drivers/usb/gadget/function/uvc.h
> +++ b/drivers/usb/gadget/function/uvc.h
> @@ -13,6 +13,8 @@
>  #include <linux/mutex.h>
>  #include <linux/spinlock.h>
>  #include <linux/usb/composite.h>
> +#include <linux/usb/g_uvc.h>
> +#include <linux/usb/video.h>
>  #include <linux/videodev2.h>
>  #include <linux/wait.h>
>  
> @@ -95,6 +97,12 @@ struct uvc_video {
>  	unsigned int cur_ival;
>  
>  	struct mutex mutex;	/* protects frame parameters */
> +	spinlock_t frame_lock;
> +
> +	struct uvc_streaming_control probe;
> +	struct uvc_streaming_control commit;
> +
> +	int control;
>  
>  	unsigned int uvc_num_requests;
>  
> @@ -131,6 +139,8 @@ struct uvc_device {
>  	struct uvc_video video;
>  	bool func_connected;
>  	wait_queue_head_t func_connected_queue;
> +	bool setup_subscribed;
> +	bool data_subscribed;
>  
>  	struct uvcg_streaming_header *header;
>  
> @@ -187,5 +197,14 @@ extern struct uvcg_format *find_format_by_index(struct uvc_device *uvc,
>  extern struct uvcg_frame *find_frame_by_index(struct uvc_device *uvc,
>  					      struct uvcg_format *uformat,
>  					      int index);
> +extern int find_format_index(struct uvc_device *uvc,
> +			       struct uvcg_format *uformat);
> +extern int find_ival_index(struct uvcg_frame *uframe, int dwFrameInterval);
> +extern void uvc_fill_streaming_control(struct uvc_device *uvc,
> +				       struct uvc_streaming_control *ctrl,
> +				       int iframe, int iformat,
> +				       unsigned int ival);
> +extern int uvc_send_response(struct uvc_device *uvc,
> +			     struct uvc_request_data *data);
>  
>  #endif /* _UVC_GADGET_H_ */
> diff --git a/drivers/usb/gadget/function/uvc_v4l2.c b/drivers/usb/gadget/function/uvc_v4l2.c
> index 3311e98a040537..e4c4bebd2ee860 100644
> --- a/drivers/usb/gadget/function/uvc_v4l2.c
> +++ b/drivers/usb/gadget/function/uvc_v4l2.c
> @@ -90,6 +90,33 @@ struct uvcg_format *find_format_by_index(struct uvc_device *uvc, int index)
>  	return uformat;
>  }
>  
> +int find_format_index(struct uvc_device *uvc, struct uvcg_format *uformat)
> +{
> +	struct uvcg_format_ptr *format;
> +	int i = 1;
> +
> +	list_for_each_entry(format, &uvc->header->formats, entry) {
> +		if (uformat == format->fmt)
> +			return i;
> +		i++;
> +	}
> +
> +	return 0;
> +}
> +
> +int find_ival_index(struct uvcg_frame *uframe, int dwFrameInterval)
> +{
> +	int i;
> +
> +	for (i = 0; i < uframe->frame.b_frame_interval_type; i++) {
> +		if (dwFrameInterval == uframe->dw_frame_interval[i])
> +			return i + 1;
> +	}
> +
> +	/* fallback */
> +	return 1;
> +}
> +
>  struct uvcg_frame *find_frame_by_index(struct uvc_device *uvc,
>  				       struct uvcg_format *uformat,
>  				       int index)
> @@ -178,8 +205,7 @@ static struct uvcg_frame *find_closest_frame_by_size(struct uvc_device *uvc,
>   * Requests handling
>   */
>  
> -static int
> -uvc_send_response(struct uvc_device *uvc, struct uvc_request_data *data)
> +int uvc_send_response(struct uvc_device *uvc, struct uvc_request_data *data)
>  {
>  	struct usb_composite_dev *cdev = uvc->func.config->cdev;
>  	struct usb_request *req = uvc->control_req;
> @@ -221,6 +247,8 @@ uvc_v4l2_get_format(struct file *file, void *fh, struct v4l2_format *fmt)
>  	struct uvc_video *video = &uvc->video;
>  	struct uvc_format_desc *fmtdesc;
>  
> +	spin_lock(&video->frame_lock);
> +
>  	fmtdesc = to_uvc_format(video->cur_format);
>  
>  	fmt->fmt.pix.pixelformat = fmtdesc->fcc;
> @@ -231,6 +259,8 @@ uvc_v4l2_get_format(struct file *file, void *fh, struct v4l2_format *fmt)
>  	fmt->fmt.pix.sizeimage = video->imagesize;
>  	fmt->fmt.pix.priv = 0;
>  
> +	spin_unlock(&video->frame_lock);
> +
>  	return 0;
>  }
>  
> @@ -255,6 +285,7 @@ uvc_v4l2_try_format(struct file *file, void *fh, struct v4l2_format *fmt)
>  	struct uvc_video *video = &uvc->video;
>  	struct uvcg_format *uformat;
>  	struct uvcg_frame *uframe;
> +	int iformat;
>  	u8 *fcc;
>  
>  	if (fmt->type != video->queue.queue.type)
> @@ -270,6 +301,10 @@ uvc_v4l2_try_format(struct file *file, void *fh, struct v4l2_format *fmt)
>  	if (!uformat)
>  		return -EINVAL;
>  
> +	iformat = find_format_index(uvc, uformat);
> +	if (!iformat)
> +		return -EINVAL;
> +
>  	uframe = find_closest_frame_by_size(uvc, uformat,
>  				fmt->fmt.pix.width, fmt->fmt.pix.height);
>  	if (!uframe)
> @@ -314,8 +349,12 @@ uvc_v4l2_enum_frameintervals(struct file *file, void *fh,
>  		if (fival->index >= 1)
>  			return -EINVAL;
>  
> +		spin_lock(&video->frame_lock);
> +
>  		fival->discrete.numerator =
>  			uframe->dw_frame_interval[video->cur_ival - 1];
> +
> +		spin_unlock(&video->frame_lock);
>  	} else {
>  		if (fival->index >= uframe->frame.b_frame_interval_type)
>  			return -EINVAL;
> @@ -347,8 +386,12 @@ uvc_v4l2_enum_framesizes(struct file *file, void *fh,
>  		if (fsize->index >= 1)
>  			return -EINVAL;
>  
> +		spin_lock(&video->frame_lock);
> +
>  		uformat = video->cur_format;
>  		uframe = video->cur_frame;
> +
> +		spin_unlock(&video->frame_lock);
>  	} else {
>  		uformat = find_format_by_pix(uvc, fsize->pixel_format);
>  		if (!uformat)
> @@ -382,7 +425,11 @@ uvc_v4l2_enum_fmt(struct file *file, void *fh, struct v4l2_fmtdesc *f)
>  		if (f->index >= 1)
>  			return -EINVAL;
>  
> +		spin_lock(&video->frame_lock);
> +
>  		uformat = video->cur_format;
> +
> +		spin_unlock(&video->frame_lock);
>  	} else {
>  		if (f->index >= uvc->header->num_fmt)
>  			return -EINVAL;
> @@ -506,14 +553,20 @@ uvc_v4l2_subscribe_event(struct v4l2_fh *fh,
>  	if (sub->type < UVC_EVENT_FIRST || sub->type > UVC_EVENT_LAST)
>  		return -EINVAL;
>  
> -	if (sub->type == UVC_EVENT_SETUP && uvc->func_connected)
> +	if (sub->type == UVC_EVENT_STREAMON && uvc->func_connected)
>  		return -EBUSY;
>  
>  	ret = v4l2_event_subscribe(fh, sub, 2, NULL);
>  	if (ret < 0)
>  		return ret;
>  
> -	if (sub->type == UVC_EVENT_SETUP) {
> +	if (sub->type == UVC_EVENT_SETUP)
> +		uvc->setup_subscribed = true;
> +
> +	if (sub->type == UVC_EVENT_DATA)
> +		uvc->data_subscribed = true;
> +
> +	if (sub->type == UVC_EVENT_STREAMON) {
>  		uvc->func_connected = true;
>  		handle->is_uvc_app_handle = true;
>  		uvc_function_connect(uvc);
> @@ -543,7 +596,10 @@ uvc_v4l2_unsubscribe_event(struct v4l2_fh *fh,
>  	if (ret < 0)
>  		return ret;
>  
> -	if (sub->type == UVC_EVENT_SETUP && handle->is_uvc_app_handle) {
> +	if (sub->type == UVC_EVENT_SETUP)
> +		uvc->setup_subscribed = false;
> +
> +	if (sub->type == UVC_EVENT_STREAMON && handle->is_uvc_app_handle) {
>  		uvc_v4l2_disable(uvc);
>  		handle->is_uvc_app_handle = false;
>  	}
> diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c
> index 37867c93073418..c20d832c4a0b8a 100644
> --- a/drivers/usb/gadget/function/uvc_video.c
> +++ b/drivers/usb/gadget/function/uvc_video.c
> @@ -533,10 +533,11 @@ static int uvc_default_frame_interval(struct uvc_video *video)
>   */
>  int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc)
>  {
> -	int iframe;
> +	int iframe, iformat;
>  
>  	INIT_LIST_HEAD(&video->req_free);
>  	spin_lock_init(&video->req_lock);
> +	spin_lock_init(&video->frame_lock);
>  	INIT_WORK(&video->pump, uvcg_video_pump);
>  
>  	if (list_empty(&uvc->header->formats))
> @@ -547,6 +548,10 @@ int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc)
>  	if (!video->cur_format)
>  		return -EINVAL;
>  
> +	iformat = find_format_index(uvc, video->cur_format);
> +	if (!iformat)
> +		return -EINVAL;
> +
>  	iframe = uvc_frame_default(video->cur_format);
>  	if (!iframe)
>  		return -EINVAL;
> @@ -557,6 +562,11 @@ int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc)
>  
>  	video->cur_ival = uvc_default_frame_interval(video);
>  
> +	uvc_fill_streaming_control(uvc, &video->probe, iframe, iformat,
> +				   video->cur_ival);
> +	uvc_fill_streaming_control(uvc, &video->commit, iframe, iformat,
> +				   video->cur_ival);
> +
>  	/* Initialize the video buffers queue. */
>  	uvcg_queue_init(&video->queue, uvc->v4l2_dev.dev->parent,
>  			V4L2_BUF_TYPE_VIDEO_OUTPUT, &video->mutex);

-- 
Regards,

Laurent Pinchart



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