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

[Kieran Bingham]

On 09/08/2019 23:48, Laurent Pinchart wrote:
> 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 ?

Yes, probably. I'll update.

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

-- 
Regards
--
Kieran