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@xxxxxx>
> ---
> 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
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
