ADV7511/13 implementing atomic ops and bus formats

[Jesse Van Gavere]

Hey all,

For one of our new boards I have to get the ADV7513 chip working with TIDSS, the driver for this expects a bridge chip to have atomic ops and provide bus formats.
Doing this for our own needs was quite straightforward but I'd very much like to upstream this as I think it could be helpful for others as well,
I do have some questions I hope to get some answers on that could help me in writing an initial patch.
I hope you'll forgive any ignorance on my end as it's my first foray into DRI.

- For all needed atomic ops I added the drm atomic ops helpers, except for atomic_check, looking through the
other implementations I can't quite figure out what I'm expected to implement here, what is the expectation for
this function?
- Looking at the lontium 9611, only the input bus formats bridge function are added there, which seems sensible
as the output goes out straight over HDMI, is it a correct assumption I'd only have to add the input bus formats for
the adv7511 driver? Part of me thinks this might not necessarily be correct as it seems the chip can be chained further
than merely to a connector and I'm not sure what this would (or could) expect
- Does Input justification matter for the bus format? My assumption is that left/evenly/right does not matter for the
format as it only relates to which pins are used and it's e.g. MEDIA_BUS_FMT_UYVY8_2X8 no matter which pins this is placed at
so I should just focus on the actively used pins.
- As it's a common driver for adv7511(w)/adv7513, would anyone know if they all use the exact same types of input styles
(of course with varying color depth support) so that I could use ADV7511 as a sort of superset for all possibilities and work
from there to define all the input formats?
- There seem to be certain formats in there that don't exist yet, such as YUV444 12-bit VYU (if I do this right and read highest data bits to lowest,
which I assume translates to MEDIA_BUS_FMT_VYU12_1X36), should I just write a patch for all missing formats to the uapi media-bus-format header
or is there anything else to take into consideration?

Best regards,
Jesse
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