Re: [PATCH v7 2/2] Driver for ON Semi AR0521 camera sensor

Krzysztof Hałasa
2022-03-01T12:19:28Z

Jacopo Mondi <jacopo@jmondi.org> writes:

>> They can. It appears, though, that clusters aren't about controls which
>> can't change independently. Both of the two are written to the hardware
>> at the same time, which appears to be a valid reason to combine them
>> into a cluster.
>
> Is there a reason to write them to hw at the same time ? :)

Sure, they are written in a single merged burst on I2C.

> As it doesn't seem to me you access registers during probe (to
> identify the sensor in example) there's no need to power up the device
> during probe, but should be enough to let runtime_pm do so when
> requested.

Yes, in fact I never try to read anything from the sensor :-)
Unfortunately I'm not sure how to initialize the (possibly nonexistent)
PM without powering it up, cleanly, in all kernel configs. I mean, I can
check if PM failed and power it up "by hand", but it's a bit messy.

Suggestions are welcome, though.
--
Krzysztof "Chris" Hałasa

Sieć Badawcza Łukasiewicz
Przemysłowy Instytut Automatyki i Pomiarów PIAP
Al. Jerozolimskie 202, 02-486 Warszawa