[libcamera-devel] [PATCH v2 1/6] libcamera: v4l2_device: Add setFd()

[Laurent Pinchart]

Hi Kieran,

Thank you for the patch.

On Fri, Aug 09, 2019 at 04:04:54PM +0100, Kieran Bingham wrote:
> Provide a means for V4L2 device instances to set the fd_ explicitly.
> This allows for V4L2Devices to operate when they must use an external
> open() call.
> 
> Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>
> ---
>  src/libcamera/include/v4l2_device.h |  1 +
>  src/libcamera/v4l2_device.cpp       | 26 ++++++++++++++++++++++++++
>  2 files changed, 27 insertions(+)
> 
> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> index e7e9829cb05f..7c3af5f6ebe0 100644
> --- a/src/libcamera/include/v4l2_device.h
> +++ b/src/libcamera/include/v4l2_device.h
> @@ -39,6 +39,7 @@ protected:
>  	int ioctl(unsigned long request, void *argp);
>  
>  	int fd() { return fd_; }
> +	int setFd(int fd);
>  
>  private:
>  	void listControls();
> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> index 9a00566a532b..ba4c0d725752 100644
> --- a/src/libcamera/v4l2_device.cpp
> +++ b/src/libcamera/v4l2_device.cpp
> @@ -308,6 +308,32 @@ int V4L2Device::ioctl(unsigned long request, void *argp)
>   * \return The V4L2 device file descriptor, -1 if the device node is not open
>   */
>  
> +/**
> + * \brief Set the file descriptor of a V4L2 device
> + * \param[in] fd The file descriptor handle
> + *
> + * This method allows a device to provide an already opened file descriptor
> + * referring to the V4L2 device node, instead of opening it with open(). This
> + * can be used for V4L2 M2M devices where a single video device node is used for
> + * both the output and capture devices, or when receiving an open file
> + * descriptor in a context that doesn't have permission to open the device node
> + * itself.
> + *
> + * This method and the open() method are mutually exclusive, only one of the two
> + * shall be used for a V4L2Device instance.
> + *
> + * \return 0 on success or a negative error code otherwise
> + */
> +int V4L2Device::setFd(int fd)
> +{
> +	if (fd_ != -1)
> +		return -1;

Just one more comment, would -EBUSY be more appropriate ?

> +
> +	fd_ = fd;
> +
> +	return 0;
> +}
> +
>  /*
>   * \brief List and store information about all controls supported by the
>   * V4L2 device

-- 
Regards,

Laurent Pinchart