Re: exposing a large-ish calibration table through V4L2?

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Hi Florian,

On 14/02/18 13:09, Florian Echtler wrote:
> Hello Hans,
> 
> I've picked up work on the sur40 driver again recently. There is one major
> feature left that is currently unsupported by the Linux driver, which is the
> hardware-based calibration.
> 
> The internal device memory contains a table with two bytes for each sensor pixel
> (i.e. 960x540x2 = 1036800 bytes) that basically provide individual black and
> white levels per-pixel that are used in preprocessing. The table can either be
> set externally, or the sensor can be covered with a black/white surface and a
> custom command triggers an internal calibration.
> 
> AFAICT the usual V4L2 controls are unsuitable for this sort of data; do you have
> any suggestions on how to approach this? Maybe something like a custom IOCTL?

So the table has a fixed size?

You can use array controls for that, a V4L2_CTRL_TYPE_U16 in a two-dimensional array
would do it.

See https://hverkuil.home.xs4all.nl/spec/uapi/v4l/vidioc-queryctrl.html for more
information on how this works.

Regards,

	Hans



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