Re: [PATCH v3 1/2] media: v4l2-ctrls: Add V4L2_CID_NOTIFY_GAIN_XXX controls

[Sakari Ailus <sakari.ailus@iki.fi>]

Hi David, Laurent,

On Thu, Aug 05, 2021 at 06:22:32PM +0300, Laurent Pinchart wrote:
> Hi David,
> 
> Thank you for the patch.
> 
> On Thu, Jul 22, 2021 at 01:12:48PM +0100, David Plowman wrote:
> > We add new controls, one for each of the four usual Bayer channels:
> > 
> > V4L2_CID_NOTIFY_GAIN_RED
> > V4L2_CID_NOTIFY_GAIN_GREENR
> > V4L2_CID_NOTIFY_GAIN_BLUE
> > V4L2_CID_NOTIFY_GAIN_GREENB
> 
> This will effectively limit the API to Bayer patterns. I wonder if we
> should instead implement it as a single array control, with one element
> per CFA component.

There are other raw patterns, too. Supporting them would likely require one
or a few more controls.

That said, as the values change often it's more efficient to use a single
control. But each colour combination (not each pattern) would require its
own control in this case, eventually requiring more controls.

Given that the number of sensors using non-Bayer patterns but still produce
Bayer output is likely to grow, these could be used by a number of devices.
I'd hence prefer an array control as well.

-- 
Kind regards,

Sakari Ailus