* [RFC] [sur40] mapping of sensor parameters to V4L2?
@ 2017-01-03 12:57 Florian Echtler
2017-01-09 14:57 ` Hans Verkuil
0 siblings, 1 reply; 2+ messages in thread
From: Florian Echtler @ 2017-01-03 12:57 UTC (permalink / raw)
To: linux-media; +Cc: modin, benjamin.tissoires, hans.verkuil
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_."
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [RFC] [sur40] mapping of sensor parameters to V4L2?
2017-01-03 12:57 [RFC] [sur40] mapping of sensor parameters to V4L2? Florian Echtler
@ 2017-01-09 14:57 ` Hans Verkuil
0 siblings, 0 replies; 2+ messages in thread
From: Hans Verkuil @ 2017-01-09 14:57 UTC (permalink / raw)
To: Florian Echtler, linux-media; +Cc: modin, benjamin.tissoires, 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
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