[RFC] ISP lane shifter support

[Michael Jones <michael.jones@matrix-vision.de>]

Hi all,

In the OMAP ISP driver, I'm interested in being able to choose between
8-bit and 12-bit formats when I have a 12-bit sensor attached.  At the
moment it looks like it's only possible to define this statically with
data_lane_shift in the board definition.  But with the ISP's lane
shifter, it should be possible for the application to ask for 8-bits
although it has a 12-bit sensor attached.

Has anybody already begun implementing this functionality?

One approach that comes to mind is to create a subdev for the
bridge/lane shifter in front of the CCDC, but this also seems a bit
overkill.  Otherwise, perhaps consider the lane shifter a part of the
CCDC and put the code in there?  Then ccdc_try_format() would have to
check whether the sink pad has a pixel format which is shiftable to the
requested pixel format on the source pad.  A problem with this might be
if there are architectures which have a CCDC but no shifter.

Are there other approaches I'm not considering?  Or problems I'm
overlooking?

Also- it looks like the CCDC now supports writing 12-bit bayer
data to memory.  Is that true?

thanks for your thoughts,
Michael

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