Hi Laurent and Chris,
Laurent Pinchart wrote:
On Wednesday 26 September 2012 07:42:41 Chris MacGregor wrote:
...
Sorry to make this more complicated, but the Aptina MT9P031, for
instance (datasheet at
http://www.aptina.com/assets/downloadDocument.do?id=865 - see page 35),
has Digital Gain, an Analog Multiplier, and Analog Gain (for each of R,
Gr, Gb, and B). For each color channel, there is one register, with the
bits divided up into the three gain types. Furthermore, the different
gain types have different units (increments).
Currently (at least in the last version I've used), the driver hides all
this and provides a single gain control, and prioritizes which gain
types are adjusted at different user-level gain settings in accordance
with the datasheet recommendations (e.g. keep the analog gain between 1
and 4 for best noise performance, and use the multiplier for gains
between 4 and 8). This seems very sensible.
I think it should be fine for now. If we later find out that a user space
application really needs to control the analog and digital gains individually
and precisely we can always split the controls then. For now I think a single
gain control (per channel) that groups analog and digital gains should be
enough.
Agreed. I think there's much less reason to keep them separate for
per-colour controls (compared to global gain), so little it's probably
not worth it.
Cheers,
--
Sakari Ailus
sakari.ai...@iki.fi
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