[PATCH 1/1] usb: gadget/uvc: Add support for 'USB_GADGET_DELAYED_STATUS' response for a set_intf(alt-set 1) command

[PATCH 1/1] usb: gadget/uvc: Add support for 'USB_GADGET_DELAYED_STATUS' response for a set_intf(alt-set 1) command

[Bhupesh Sharma]

This patch adds the support in UVC webcam gadget design for providing
USB_GADGET_DELAYED_STATUS in response to a set_interface(alt setting 1) command
issue by the Host.

The current UVC webcam gadget design generates a STREAMON event corresponding
to a set_interface(alt setting 1) command from the Host.
This STREAMON event will eventually be routed to a real V4L2 device.

To start video streaming, it may be required to perform some register writes to
a camera sensor device over slow external busses like I2C or SPI. So, it makes
sense to ensure that we delay the STATUS stage of the
set_interface(alt setting 1) command.

Otherwise, a lot of ISOC IN tokens sent by the Host will be replied to by
zero-length packets by the webcam device. On certain Hosts this may even lead to
ISOC URBs been cancelled from the Host side.

So, as soon as we finish doing all the "streaming" related stuff on the real
V4L2 device, we call a STREAMON ioctl on the UVC side and from here we call
the 'usb_composite_setup_continue' function to complete the status stage of
the set_interface(alt setting 1) command.

Signed-off-by: Bhupesh Sharma <bhupesh.sharma@st.com>
---
 drivers/usb/gadget/f_uvc.c    |   12 +++++++++++-
 drivers/usb/gadget/uvc.h      |    4 ++++
 drivers/usb/gadget/uvc_v4l2.c |   27 +++++++++++++++++++++++++--
 3 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/f_uvc.c b/drivers/usb/gadget/f_uvc.c
index d2569b2..6f084e3 100644
--- a/drivers/usb/gadget/f_uvc.c
+++ b/drivers/usb/gadget/f_uvc.c
@@ -209,6 +209,14 @@ uvc_function_get_alt(struct usb_function *f, unsigned interface)
 		return uvc->state == UVC_STATE_STREAMING ? 1 : 0;
 }
 
+void
+uvc_process_setup_continue(struct uvc_device *uvc)
+{
+	struct usb_composite_dev *cdev = uvc->func.config->cdev;
+
+	usb_composite_setup_continue(cdev);
+}
+
 static int
 uvc_function_set_alt(struct usb_function *f, unsigned interface, unsigned alt)
 {
@@ -271,7 +279,9 @@ uvc_function_set_alt(struct usb_function *f, unsigned interface, unsigned alt)
 		v4l2_event_queue(uvc->vdev, &v4l2_event);
 
 		uvc->state = UVC_STATE_STREAMING;
-		break;
+		uvc->vdev_is_streaming = false;
+
+		return USB_GADGET_DELAYED_STATUS;
 
 	default:
 		return -EINVAL;
diff --git a/drivers/usb/gadget/uvc.h b/drivers/usb/gadget/uvc.h
index bc78c60..56ac883 100644
--- a/drivers/usb/gadget/uvc.h
+++ b/drivers/usb/gadget/uvc.h
@@ -168,6 +168,9 @@ struct uvc_device
 	/* Events */
 	unsigned int event_length;
 	unsigned int event_setup_out : 1;
+
+	/* flags */
+	bool vdev_is_streaming;
 };
 
 static inline struct uvc_device *to_uvc(struct usb_function *f)
@@ -188,6 +191,7 @@ struct uvc_file_handle
  * Functions
  */
 
+extern void uvc_process_setup_continue(struct uvc_device *uvc);
 extern void uvc_endpoint_stream(struct uvc_device *dev);
 
 extern void uvc_function_connect(struct uvc_device *uvc);
diff --git a/drivers/usb/gadget/uvc_v4l2.c b/drivers/usb/gadget/uvc_v4l2.c
index f761bcb..379d8ac 100644
--- a/drivers/usb/gadget/uvc_v4l2.c
+++ b/drivers/usb/gadget/uvc_v4l2.c
@@ -242,7 +242,18 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
 		if ((ret = uvc_queue_buffer(&video->queue, arg)) < 0)
 			return ret;
 
-		return uvc_video_pump(video);
+		/*
+		 * for the very first QBUF calls (until STREAMON is
+		 * called) we just need to queue the buffers and start
+		 * pumping the data to USB side only after STREAMON has
+		 * been called which is handled by the STREAMON case
+		 * below. For QBUF calls after STREAMON, we need to pump
+		 * the data to the USB side here itself.
+		 */
+		if (uvc->vdev_is_streaming)
+			return uvc_video_pump(video);
+
+		return 0;
 
 	case VIDIOC_DQBUF:
 		return uvc_dequeue_buffer(&video->queue, arg,
@@ -255,7 +266,19 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
 		if (*type != video->queue.type)
 			return -EINVAL;
 
-		return uvc_video_enable(video, 1);
+		ret = uvc_video_enable(video, 1);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * since the real video device has now started streaming
+		 * its safe now to complete the status phase of the
+		 * set_interface (alt setting 1)
+		 */
+		uvc_process_setup_continue(uvc);
+		uvc->vdev_is_streaming = true;
+
+		return 0;
 	}
 
 	case VIDIOC_STREAMOFF:
-- 
1.7.2.2

RE: [PATCH 1/1] usb: gadget/uvc: Add support for 'USB_GADGET_DELAYED_STATUS' response for a set_intf(alt-set 1) command

[Bhupesh SHARMA]

Hi Laurent,

I know you are very busy these days with the dmabuf, vb2 and v4l2 stuff :)
But, can you please have a look at this patch and let me know if this
is ok or do I need to do some modifications in the same.

Regards,
Bhupesh

> -----Original Message-----
> From: Bhupesh SHARMA
> Sent: Monday, May 07, 2012 12:43 PM
> To: laurent.pinchart@ideasonboard.com; linux-usb@vger.kernel.org
> Cc: balbi@ti.com; linux-kernel@vger.kernel.org; Bhupesh SHARMA
> Subject: [PATCH 1/1] usb: gadget/uvc: Add support for
> 'USB_GADGET_DELAYED_STATUS' response for a set_intf(alt-set 1) command
> 
> This patch adds the support in UVC webcam gadget design for providing
> USB_GADGET_DELAYED_STATUS in response to a set_interface(alt setting 1)
> command
> issue by the Host.
> 
> The current UVC webcam gadget design generates a STREAMON event
> corresponding
> to a set_interface(alt setting 1) command from the Host.
> This STREAMON event will eventually be routed to a real V4L2 device.
> 
> To start video streaming, it may be required to perform some register
> writes to
> a camera sensor device over slow external busses like I2C or SPI. So,
> it makes
> sense to ensure that we delay the STATUS stage of the
> set_interface(alt setting 1) command.
> 
> Otherwise, a lot of ISOC IN tokens sent by the Host will be replied to
> by
> zero-length packets by the webcam device. On certain Hosts this may
> even lead to
> ISOC URBs been cancelled from the Host side.
> 
> So, as soon as we finish doing all the "streaming" related stuff on the
> real
> V4L2 device, we call a STREAMON ioctl on the UVC side and from here we
> call
> the 'usb_composite_setup_continue' function to complete the status
> stage of
> the set_interface(alt setting 1) command.
> 
> Signed-off-by: Bhupesh Sharma <bhupesh.sharma@st.com>
> ---
>  drivers/usb/gadget/f_uvc.c    |   12 +++++++++++-
>  drivers/usb/gadget/uvc.h      |    4 ++++
>  drivers/usb/gadget/uvc_v4l2.c |   27 +++++++++++++++++++++++++--
>  3 files changed, 40 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/gadget/f_uvc.c b/drivers/usb/gadget/f_uvc.c
> index d2569b2..6f084e3 100644
> --- a/drivers/usb/gadget/f_uvc.c
> +++ b/drivers/usb/gadget/f_uvc.c
> @@ -209,6 +209,14 @@ uvc_function_get_alt(struct usb_function *f,
> unsigned interface)
>  		return uvc->state == UVC_STATE_STREAMING ? 1 : 0;
>  }
> 
> +void
> +uvc_process_setup_continue(struct uvc_device *uvc)
> +{
> +	struct usb_composite_dev *cdev = uvc->func.config->cdev;
> +
> +	usb_composite_setup_continue(cdev);
> +}
> +
>  static int
>  uvc_function_set_alt(struct usb_function *f, unsigned interface,
> unsigned alt)
>  {
> @@ -271,7 +279,9 @@ uvc_function_set_alt(struct usb_function *f,
> unsigned interface, unsigned alt)
>  		v4l2_event_queue(uvc->vdev, &v4l2_event);
> 
>  		uvc->state = UVC_STATE_STREAMING;
> -		break;
> +		uvc->vdev_is_streaming = false;
> +
> +		return USB_GADGET_DELAYED_STATUS;
> 
>  	default:
>  		return -EINVAL;
> diff --git a/drivers/usb/gadget/uvc.h b/drivers/usb/gadget/uvc.h
> index bc78c60..56ac883 100644
> --- a/drivers/usb/gadget/uvc.h
> +++ b/drivers/usb/gadget/uvc.h
> @@ -168,6 +168,9 @@ struct uvc_device
>  	/* Events */
>  	unsigned int event_length;
>  	unsigned int event_setup_out : 1;
> +
> +	/* flags */
> +	bool vdev_is_streaming;
>  };
> 
>  static inline struct uvc_device *to_uvc(struct usb_function *f)
> @@ -188,6 +191,7 @@ struct uvc_file_handle
>   * Functions
>   */
> 
> +extern void uvc_process_setup_continue(struct uvc_device *uvc);
>  extern void uvc_endpoint_stream(struct uvc_device *dev);
> 
>  extern void uvc_function_connect(struct uvc_device *uvc);
> diff --git a/drivers/usb/gadget/uvc_v4l2.c
> b/drivers/usb/gadget/uvc_v4l2.c
> index f761bcb..379d8ac 100644
> --- a/drivers/usb/gadget/uvc_v4l2.c
> +++ b/drivers/usb/gadget/uvc_v4l2.c
> @@ -242,7 +242,18 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int
> cmd, void *arg)
>  		if ((ret = uvc_queue_buffer(&video->queue, arg)) < 0)
>  			return ret;
> 
> -		return uvc_video_pump(video);
> +		/*
> +		 * for the very first QBUF calls (until STREAMON is
> +		 * called) we just need to queue the buffers and start
> +		 * pumping the data to USB side only after STREAMON has
> +		 * been called which is handled by the STREAMON case
> +		 * below. For QBUF calls after STREAMON, we need to pump
> +		 * the data to the USB side here itself.
> +		 */
> +		if (uvc->vdev_is_streaming)
> +			return uvc_video_pump(video);
> +
> +		return 0;
> 
>  	case VIDIOC_DQBUF:
>  		return uvc_dequeue_buffer(&video->queue, arg,
> @@ -255,7 +266,19 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int
> cmd, void *arg)
>  		if (*type != video->queue.type)
>  			return -EINVAL;
> 
> -		return uvc_video_enable(video, 1);
> +		ret = uvc_video_enable(video, 1);
> +		if (ret < 0)
> +			return ret;
> +
> +		/*
> +		 * since the real video device has now started streaming
> +		 * its safe now to complete the status phase of the
> +		 * set_interface (alt setting 1)
> +		 */
> +		uvc_process_setup_continue(uvc);
> +		uvc->vdev_is_streaming = true;
> +
> +		return 0;
>  	}
> 
>  	case VIDIOC_STREAMOFF:
> --
> 1.7.2.2

Re: [PATCH 1/1] usb: gadget/uvc: Add support for 'USB_GADGET_DELAYED_STATUS' response for a set_intf(alt-set 1) command

[Laurent Pinchart]

Hi Bhupesh,

Thank you for the patch.

On Monday 07 May 2012 12:42:37 Bhupesh Sharma wrote:
> This patch adds the support in UVC webcam gadget design for providing
> USB_GADGET_DELAYED_STATUS in response to a set_interface(alt setting 1)
> command issue by the Host.
> 
> The current UVC webcam gadget design generates a STREAMON event
> corresponding to a set_interface(alt setting 1) command from the Host.
> This STREAMON event will eventually be routed to a real V4L2 device.
> 
> To start video streaming, it may be required to perform some register writes
> to a camera sensor device over slow external busses like I2C or SPI. So, it
> makes sense to ensure that we delay the STATUS stage of the
> set_interface(alt setting 1) command.
> 
> Otherwise, a lot of ISOC IN tokens sent by the Host will be replied to by
> zero-length packets by the webcam device. On certain Hosts this may even
> lead to ISOC URBs been cancelled from the Host side.

Very good point.

> So, as soon as we finish doing all the "streaming" related stuff on the real
> V4L2 device, we call a STREAMON ioctl on the UVC side and from here we call
> the 'usb_composite_setup_continue' function to complete the status stage of
> the set_interface(alt setting 1) command.
> 
> Signed-off-by: Bhupesh Sharma <bhupesh.sharma@st.com>
> ---
>  drivers/usb/gadget/f_uvc.c    |   12 +++++++++++-
>  drivers/usb/gadget/uvc.h      |    4 ++++
>  drivers/usb/gadget/uvc_v4l2.c |   27 +++++++++++++++++++++++++--
>  3 files changed, 40 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/gadget/f_uvc.c b/drivers/usb/gadget/f_uvc.c
> index d2569b2..6f084e3 100644
> --- a/drivers/usb/gadget/f_uvc.c
> +++ b/drivers/usb/gadget/f_uvc.c
> @@ -209,6 +209,14 @@ uvc_function_get_alt(struct usb_function *f, unsigned
> interface) return uvc->state == UVC_STATE_STREAMING ? 1 : 0;
>  }
> 
> +void
> +uvc_process_setup_continue(struct uvc_device *uvc)

No need for a line split, this won't exceed the 80 columns limit.

Could you please rename the function to uvc_function_setup_continue to be 
coherent with the other non-static functions in this file (and, while you're 
at it, move it right above uvc_function_get_alt) ?

> +{
> +	struct usb_composite_dev *cdev = uvc->func.config->cdev;
> +
> +	usb_composite_setup_continue(cdev);
> +}
> +
>  static int
>  uvc_function_set_alt(struct usb_function *f, unsigned interface, unsigned
> alt) {
> @@ -271,7 +279,9 @@ uvc_function_set_alt(struct usb_function *f, unsigned
> interface, unsigned alt) v4l2_event_queue(uvc->vdev, &v4l2_event);
> 
>  		uvc->state = UVC_STATE_STREAMING;
> -		break;
> +		uvc->vdev_is_streaming = false;

Do you think you could combine the state and vdev_is_streaming fields ? Maybe 
adding a UVC_STATE_PRE_STREAMING state would be enough, you could set the 
state to that value here, and then set it to UVC_STATE_STREAMING in the 
STREAMON ioctl handler (I would actually prefer doing that in the 
uvc_video_enable function).

If you think it makes sense, could you please try it ?

> +
> +		return USB_GADGET_DELAYED_STATUS;

Could you please move the return 0 at the end of this function to the case 0 
above ? Each case will then have its return statement.

>  	default:
>  		return -EINVAL;
> diff --git a/drivers/usb/gadget/uvc.h b/drivers/usb/gadget/uvc.h
> index bc78c60..56ac883 100644
> --- a/drivers/usb/gadget/uvc.h
> +++ b/drivers/usb/gadget/uvc.h
> @@ -168,6 +168,9 @@ struct uvc_device
>  	/* Events */
>  	unsigned int event_length;
>  	unsigned int event_setup_out : 1;
> +
> +	/* flags */
> +	bool vdev_is_streaming;
>  };
> 
>  static inline struct uvc_device *to_uvc(struct usb_function *f)
> @@ -188,6 +191,7 @@ struct uvc_file_handle
>   * Functions
>   */
> 
> +extern void uvc_process_setup_continue(struct uvc_device *uvc);
>  extern void uvc_endpoint_stream(struct uvc_device *dev);
> 
>  extern void uvc_function_connect(struct uvc_device *uvc);
> diff --git a/drivers/usb/gadget/uvc_v4l2.c b/drivers/usb/gadget/uvc_v4l2.c
> index f761bcb..379d8ac 100644
> --- a/drivers/usb/gadget/uvc_v4l2.c
> +++ b/drivers/usb/gadget/uvc_v4l2.c
> @@ -242,7 +242,18 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd,
> void *arg) if ((ret = uvc_queue_buffer(&video->queue, arg)) < 0)
>  			return ret;
> 
> -		return uvc_video_pump(video);
> +		/*
> +		 * for the very first QBUF calls (until STREAMON is
> +		 * called) we just need to queue the buffers and start
> +		 * pumping the data to USB side only after STREAMON has
> +		 * been called which is handled by the STREAMON case
> +		 * below. For QBUF calls after STREAMON, we need to pump
> +		 * the data to the USB side here itself.
> +		 */
> +		if (uvc->vdev_is_streaming)
> +			return uvc_video_pump(video);
> +
> +		return 0;
> 
>  	case VIDIOC_DQBUF:
>  		return uvc_dequeue_buffer(&video->queue, arg,
> @@ -255,7 +266,19 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd,
> void *arg) if (*type != video->queue.type)
>  			return -EINVAL;
> 
> -		return uvc_video_enable(video, 1);
> +		ret = uvc_video_enable(video, 1);
> +		if (ret < 0)
> +			return ret;
> +
> +		/*
> +		 * since the real video device has now started streaming
> +		 * its safe now to complete the status phase of the
> +		 * set_interface (alt setting 1)
> +		 */
> +		uvc_process_setup_continue(uvc);
> +		uvc->vdev_is_streaming = true;

Could you please move this to uvc_video_enable() ?

> +
> +		return 0;
>  	}
> 
>  	case VIDIOC_STREAMOFF:

-- 
Regards,

Laurent Pinchart

RE: [PATCH 1/1] usb: gadget/uvc: Add support for 'USB_GADGET_DELAYED_STATUS' response for a set_intf(alt-set 1) command

[Bhupesh SHARMA]

Hi Laurent,

Thanks for your review.

> -----Original Message-----
> From: Laurent Pinchart [mailto:laurent.pinchart@ideasonboard.com]
> Sent: Friday, May 18, 2012 4:21 AM
> To: Bhupesh SHARMA
> Cc: linux-usb@vger.kernel.org; balbi@ti.com; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH 1/1] usb: gadget/uvc: Add support for
> 'USB_GADGET_DELAYED_STATUS' response for a set_intf(alt-set 1) command
> 
> Hi Bhupesh,
> 
> Thank you for the patch.
> 
> On Monday 07 May 2012 12:42:37 Bhupesh Sharma wrote:
> > This patch adds the support in UVC webcam gadget design for providing
> > USB_GADGET_DELAYED_STATUS in response to a set_interface(alt setting
> 1)
> > command issue by the Host.
> >
> > The current UVC webcam gadget design generates a STREAMON event
> > corresponding to a set_interface(alt setting 1) command from the
> Host.
> > This STREAMON event will eventually be routed to a real V4L2 device.
> >
> > To start video streaming, it may be required to perform some register
> writes
> > to a camera sensor device over slow external busses like I2C or SPI.
> So, it
> > makes sense to ensure that we delay the STATUS stage of the
> > set_interface(alt setting 1) command.
> >
> > Otherwise, a lot of ISOC IN tokens sent by the Host will be replied
> to by
> > zero-length packets by the webcam device. On certain Hosts this may
> even
> > lead to ISOC URBs been cancelled from the Host side.
> 
> Very good point.
> 
> > So, as soon as we finish doing all the "streaming" related stuff on
> the real
> > V4L2 device, we call a STREAMON ioctl on the UVC side and from here
> we call
> > the 'usb_composite_setup_continue' function to complete the status
> stage of
> > the set_interface(alt setting 1) command.
> >
> > Signed-off-by: Bhupesh Sharma <bhupesh.sharma@st.com>
> > ---
> >  drivers/usb/gadget/f_uvc.c    |   12 +++++++++++-
> >  drivers/usb/gadget/uvc.h      |    4 ++++
> >  drivers/usb/gadget/uvc_v4l2.c |   27 +++++++++++++++++++++++++--
> >  3 files changed, 40 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/f_uvc.c b/drivers/usb/gadget/f_uvc.c
> > index d2569b2..6f084e3 100644
> > --- a/drivers/usb/gadget/f_uvc.c
> > +++ b/drivers/usb/gadget/f_uvc.c
> > @@ -209,6 +209,14 @@ uvc_function_get_alt(struct usb_function *f,
> unsigned
> > interface) return uvc->state == UVC_STATE_STREAMING ? 1 : 0;
> >  }
> >
> > +void
> > +uvc_process_setup_continue(struct uvc_device *uvc)
> 
> No need for a line split, this won't exceed the 80 columns limit.

I just wanted to be in sync with existing function definition in UVC gadget.
But I will change this :)
 
> Could you please rename the function to uvc_function_setup_continue to
> be
> coherent with the other non-static functions in this file (and, while
> you're
> at it, move it right above uvc_function_get_alt) ?

Ok.

> > +{
> > +	struct usb_composite_dev *cdev = uvc->func.config->cdev;
> > +
> > +	usb_composite_setup_continue(cdev);
> > +}
> > +
> >  static int
> >  uvc_function_set_alt(struct usb_function *f, unsigned interface,
> unsigned
> > alt) {
> > @@ -271,7 +279,9 @@ uvc_function_set_alt(struct usb_function *f,
> unsigned
> > interface, unsigned alt) v4l2_event_queue(uvc->vdev, &v4l2_event);
> >
> >  		uvc->state = UVC_STATE_STREAMING;
> > -		break;
> > +		uvc->vdev_is_streaming = false;
> 
> Do you think you could combine the state and vdev_is_streaming fields ?
> Maybe
> adding a UVC_STATE_PRE_STREAMING state would be enough, you could set
> the
> state to that value here, and then set it to UVC_STATE_STREAMING in the
> STREAMON ioctl handler (I would actually prefer doing that in the
> uvc_video_enable function).
> 
> If you think it makes sense, could you please try it ?

Seems fine to me. I will give it a try and update my results soon.

> 
> > +
> > +		return USB_GADGET_DELAYED_STATUS;
> 
> Could you please move the return 0 at the end of this function to the
> case 0
> above ? Each case will then have its return statement.

Ok.
 
> >  	default:
> >  		return -EINVAL;
> > diff --git a/drivers/usb/gadget/uvc.h b/drivers/usb/gadget/uvc.h
> > index bc78c60..56ac883 100644
> > --- a/drivers/usb/gadget/uvc.h
> > +++ b/drivers/usb/gadget/uvc.h
> > @@ -168,6 +168,9 @@ struct uvc_device
> >  	/* Events */
> >  	unsigned int event_length;
> >  	unsigned int event_setup_out : 1;
> > +
> > +	/* flags */
> > +	bool vdev_is_streaming;
> >  };
> >
> >  static inline struct uvc_device *to_uvc(struct usb_function *f)
> > @@ -188,6 +191,7 @@ struct uvc_file_handle
> >   * Functions
> >   */
> >
> > +extern void uvc_process_setup_continue(struct uvc_device *uvc);
> >  extern void uvc_endpoint_stream(struct uvc_device *dev);
> >
> >  extern void uvc_function_connect(struct uvc_device *uvc);
> > diff --git a/drivers/usb/gadget/uvc_v4l2.c
> b/drivers/usb/gadget/uvc_v4l2.c
> > index f761bcb..379d8ac 100644
> > --- a/drivers/usb/gadget/uvc_v4l2.c
> > +++ b/drivers/usb/gadget/uvc_v4l2.c
> > @@ -242,7 +242,18 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned
> int cmd,
> > void *arg) if ((ret = uvc_queue_buffer(&video->queue, arg)) < 0)
> >  			return ret;
> >
> > -		return uvc_video_pump(video);
> > +		/*
> > +		 * for the very first QBUF calls (until STREAMON is
> > +		 * called) we just need to queue the buffers and start
> > +		 * pumping the data to USB side only after STREAMON has
> > +		 * been called which is handled by the STREAMON case
> > +		 * below. For QBUF calls after STREAMON, we need to pump
> > +		 * the data to the USB side here itself.
> > +		 */
> > +		if (uvc->vdev_is_streaming)
> > +			return uvc_video_pump(video);
> > +
> > +		return 0;
> >
> >  	case VIDIOC_DQBUF:
> >  		return uvc_dequeue_buffer(&video->queue, arg,
> > @@ -255,7 +266,19 @@ uvc_v4l2_do_ioctl(struct file *file, unsigned
> int cmd,
> > void *arg) if (*type != video->queue.type)
> >  			return -EINVAL;
> >
> > -		return uvc_video_enable(video, 1);
> > +		ret = uvc_video_enable(video, 1);
> > +		if (ret < 0)
> > +			return ret;
> > +
> > +		/*
> > +		 * since the real video device has now started streaming
> > +		 * its safe now to complete the status phase of the
> > +		 * set_interface (alt setting 1)
> > +		 */
> > +		uvc_process_setup_continue(uvc);
> > +		uvc->vdev_is_streaming = true;
> 
> Could you please move this to uvc_video_enable() ?

Ok.
 
> > +
> > +		return 0;
> >  	}
> >
> >  	case VIDIOC_STREAMOFF:
> 

Regards,
Bhupesh