[RFC] [sur40] mapping of sensor parameters to V4L2?

[RFC] [sur40] mapping of sensor parameters to V4L2?

[Florian Echtler]

Hi everyone,

next chapter in the neverending story of reverse-engineering the SUR40:

I've identified a couple of internal LCD panel registers which control 
some aspects of the built-in image sensor. In particular, these are called 
"Video Voltage", "Video Bias", and "IR Illumination Level".

Now, I have two questions:

- Video Voltage & Bias seem to affect the sensor gain. Does anyone with 
extensive background knowledge of image sensors want to venture a guess 
what the exact relation is? My own interpretation would be that Video 
Voltage is the actual amplifier gain and Video Bias is the black level...

- Is there a sensible mapping of these values to V4L2 controls? Should I 
pick something from the USER class, or from CAMERA, or FLASH, or ...

Thanks & best regards, Florian
-- 
"_Nothing_ brightens up my morning. Coffee simply provides a shade of
grey just above the pitch-black of the infinite depths of the _abyss_."

Re: [RFC] [sur40] mapping of sensor parameters to V4L2?

[Hans Verkuil]

On 01/03/2017 01:57 PM, Florian Echtler wrote:
> Hi everyone,
> 
> next chapter in the neverending story of reverse-engineering the SUR40:
> 
> I've identified a couple of internal LCD panel registers which control 
> some aspects of the built-in image sensor. In particular, these are called 
> "Video Voltage", "Video Bias", and "IR Illumination Level".
> 
> Now, I have two questions:
> 
> - Video Voltage & Bias seem to affect the sensor gain. Does anyone with 
> extensive background knowledge of image sensors want to venture a guess 
> what the exact relation is? My own interpretation would be that Video 
> Voltage is the actual amplifier gain and Video Bias is the black level...
> 
> - Is there a sensible mapping of these values to V4L2 controls? Should I 
> pick something from the USER class, or from CAMERA, or FLASH, or ...

I think it would be best to add a control class for touch device and add
these controls there.

It's pretty specific to such devices, so that would make sense.

Regards,

	Hans