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

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Date:   Thu, 6 Aug 2020 09:51:12 -0700
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        Thierry Reding <thierry.reding@...il.com>
CC:     <jonathanh@...dia.com>, <frankc@...dia.com>, <hverkuil@...all.nl>,
        <sakari.ailus@....fi>, <robh+dt@...nel.org>,
        <helen.koike@...labora.com>, <gregkh@...uxfoundation.org>,
        <linux-media@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 08/10] gpu: host1x: mipi: Keep MIPI clock enabled till
 calibration is done


On 8/6/20 9:45 AM, Dmitry Osipenko wrote:
> 06.08.2020 19:41, Sowjanya Komatineni пишет:
> ...
>>> What about to add 72us delay to the end of start_calibration() in order
>>> to ensure that FSM is finished before LP-11?
>> Why we should add 72uS in start_calibration() when can use same
>> finish_calibration() for both pass/fail cases?
>>
>> Only timing loose we see is in case of failure we still wait for 250ms
>> and as this is failing case I hope should be ok.
>>
> You said that calibration settings are applied to pads on LP-11, but if
> LP-11 happens before FSM is finished, then what values will be applied
> if any?

No calibration logic will check for LP-11 only after finishing 
calibration sequence codes.

After that if it sees LP-11, it will apply results to pads and DONE bit 
will then be set to 1 indication pad results update.

Unfortunately like I said we don't have status indication for 
calibrating finished before waiting for LP-11.

ACTIVE bit is common for all PADS. If multiple 6 streams are happening 
in parallel, ACTIVE will be 1 as long as its calibrating any of the pads 
and its not for individual pads.