Re: [PATCH v8 08/10] gpu: host1x: mipi: Keep MIPI clock enabled till calibration is done

From: Dmitry Osipenko
Date: Thu Aug 06 2020 - 12:58:36 EST

06.08.2020 18:59, Sowjanya Komatineni пишет:
>>> Confirmed from HW designer, calibration FSM to finish takes worst case
>>> 72uS so by the time it gets to sensor stream it will be done its
>>> sequence and will be waiting for DONE bit.
>>> So disabling MIPI CAL clock on sensor stream fails is safe.
>> 72us is quite a lot of time, what will happen if LP-11 happens before
>> FSM finished calibration?
>> Maybe the finish_calibration() needs to split into two parts:
>>   1. wait for CAL_STATUS_ACTIVE before enabling sensor
>>   2. wait for CAL_STATUS_DONE after enabling sensor
> I don't think we need to split for active and done. Active will be 1 as
> long as other pads are in calibration as well.
> We cant use active status check for specific pads under calibration.
> This is common bit for all pads.

Does hardware have a single FSM block shared by all pads or there is FSM
per group of pads?

> Unfortunately HW don't have separate status indicating when sequence is
> done to indicate its waiting for LP11.
> To avoid all this, will remove cancel_calibration() totally and use same
> finish calibration even in case of stream failure then.

What about to add 72us delay to the end of start_calibration() in order
to ensure that FSM is finished before LP-11?