Re: [RFC/PATCH 3/6] V4L: Add g_embedded_data subdev callback

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sylwester,

On Saturday 18 February 2012 00:33:23 Sylwester Nawrocki wrote:
> On 02/18/2012 12:23 AM, Laurent Pinchart wrote:
> >>   struct v4l2_subdev_video_ops {
> >>   
> >>   	int (*s_routing)(struct v4l2_subdev *sd, u32 input, u32 output, u32
> >> 
> >> config); @@ -321,6 +329,8 @@ struct v4l2_subdev_video_ops {
> >> 
> >>   			     struct v4l2_mbus_config *cfg);
> >>   	
> >>   	int (*s_mbus_config)(struct v4l2_subdev *sd,
> >>   	
> >>   			     const struct v4l2_mbus_config *cfg);
> >> 
> >> +	int (*g_embedded_data)(struct v4l2_subdev *sd, unsigned int *size,
> >> +			       void **buf);
> >> 
> >>   };
> > 
> > How is the embedded data transferred from the sensor to the host in your
> > case ? Over I2C ?
> 
> It's transferred over MIPI-CSI2 bus and is intercepted by the MIPI-CSI2
> receiver, before the image data DMA. The MIPI-CSI2 doesn't have its own
> DMA engine. More details can be found in patch 6/6.

As the data is transmitted by the device without any polling from the host, 
shouldn't it just go to a metadata plane in the V4L2 buffer ?

-- 
Regards,

Laurent Pinchart