Hi David, On Mon, Aug 09, 2021 at 01:31:44PM +0100, David Plowman wrote: > Hi everyone > > On Mon, 9 Aug 2021 at 13:24, Hans Verkuil <hverkuil-cisco@xxxxxxxxx> wrote: > > > > On 09/08/2021 14:19, Laurent Pinchart wrote: > > > Hi Hans, > > > > > > On Mon, Aug 09, 2021 at 01:05:00PM +0200, Hans Verkuil wrote: > > >> On 09/08/2021 11:34, David Plowman wrote: > > >>> We add a new control V4L2_CID_NOTIFY_GAINS which allows the sensor to > > >>> be notified what gains will be applied to the different colour > > >>> channels by subsequent processing (such as by an ISP), even though the > > >>> sensor will not apply any of these gains itself. > > >>> > > >>> For Bayer sensors this will be an array control taking 4 values which > > >>> are the 4 gains arranged in the fixed order B, Gb, Gr and R, > > >>> irrespective of the exact Bayer order of the sensor itself. > > >>> > > >>> The units are in all cases linear with the default value indicating a > > >>> gain of exactly 1. > > >> > > >> So a value of 2 means a gain of 2? Or are these fixed point values? How do > > >> I represent a gain of 1.5? > > > > > > No, the default value corresponds to a x1.0 gain, but it's not 1. If the > > > default is, let's say, 128, then x2.0 will be 256. > > > > Ah, now I get it. Perhaps a small example of this in the documentation patch will > > help clarify this. > > Yes I agree that would be helpful. I'll put that in the next version > shortly (just waiting to see if there are any other changes > suggested). The digital gain control has the same semantics, see Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst . -- Regards, Sakari Ailus
