From: Sowjanya Komatineni <skomatineni@nvidia.com>
To: Dmitry Osipenko <digetx@gmail.com>,
Thierry Reding <thierry.reding@gmail.com>
Cc: <jonathanh@nvidia.com>, <frankc@nvidia.com>, <hverkuil@xs4all.nl>,
<sakari.ailus@iki.fi>, <robh+dt@kernel.org>,
<helen.koike@collabora.com>, <gregkh@linuxfoundation.org>,
<linux-media@vger.kernel.org>, <devicetree@vger.kernel.org>,
<linux-tegra@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v8 08/10] gpu: host1x: mipi: Keep MIPI clock enabled till calibration is done
Date: Thu, 6 Aug 2020 10:12:16 -0700 [thread overview]
Message-ID: <61275bd6-58e7-887f-aa7d-8e60895e7b2b@nvidia.com> (raw)
In-Reply-To: <412f8c53-1aca-db31-99a1-a0ecb2081ca5@nvidia.com>
On 8/6/20 9:41 AM, Sowjanya Komatineni wrote:
>
> On 8/6/20 9:10 AM, Dmitry Osipenko wrote:
>> 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?
>
> MIPI CAL status register has DONE bits for individual pads status and
> single ACTIVE bit.
>
> ACTIVE bit set to 1 indicates auto calibration is active which is the
> case even when other pads (other CSI pads from other ports streaming
> in case of parallel stream) are under calibration. Also DSI is shared
> as well.
>
> We do calibration for individual pads. So, we should not rely on
> ACTIVE bit.
>
>
> MIPI driver checks for condition ACTIVE == 1 && DONE == 1 from the
> beginning.
>
> But I think this also should be fixed as in case of parallel streams
> calibration can happen in parallel waiting for ACTIVE to be cleared
> makes all calibration callers to wait for longer than needed as ACTIVE
> is common for all 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?
>
> 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.
>
Also as we don't need cancel_calibration(), keeping tegra_mipi_wait()
like earlier makes sense I believe as we are letting it finish going
thru sequence.
So I think below are fixes,
1. Existing MIPI driver, tegra_mipi_wait() to not use status ACTIVE bit
to be 0 and use only DONE bit to be 1 for wait condition as we are
calibrating separately for individual pads and this ACTIVE bit is common
for all pads where it will not be 0 in case of other parallel streams
which may also be under calibration.
2. No need for separate cancel_calibration. So, probably earlier names
tegra_mipi_calibrate() and tegra_mipi_wait() hols good as we are waiting
for calibration sequence to finish irrespective of fail/pass.
next prev parent reply other threads:[~2020-08-06 17:12 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-03 15:42 [PATCH v8 00/10] Support for Tegra video capture from external sensor Sowjanya Komatineni
2020-08-03 15:42 ` [PATCH v8 01/10] media: tegra-video: Fix channel format alignment Sowjanya Komatineni
2020-08-03 15:42 ` [PATCH v8 02/10] media: tegra-video: Enable TPG based on kernel config Sowjanya Komatineni
2020-08-03 15:42 ` [PATCH v8 03/10] media: tegra-video: Update format lookup to offset based Sowjanya Komatineni
2020-08-03 15:42 ` [PATCH v8 04/10] dt-bindings: tegra: Update VI and CSI bindings with port info Sowjanya Komatineni
2020-08-03 15:42 ` [PATCH v8 05/10] media: tegra-video: Separate CSI stream enable and disable implementations Sowjanya Komatineni
2020-08-03 15:42 ` [PATCH v8 06/10] media: tegra-video: Add support for external sensor capture Sowjanya Komatineni
2020-08-04 5:57 ` Dmitry Osipenko
2020-08-03 15:42 ` [PATCH v8 07/10] media: tegra-video: Add support for selection ioctl ops Sowjanya Komatineni
2020-08-03 15:42 ` [PATCH v8 08/10] gpu: host1x: mipi: Keep MIPI clock enabled till calibration is done Sowjanya Komatineni
2020-08-05 13:46 ` Thierry Reding
2020-08-05 14:05 ` Dmitry Osipenko
2020-08-05 14:19 ` Dmitry Osipenko
2020-08-05 16:33 ` Sowjanya Komatineni
2020-08-05 16:47 ` Dmitry Osipenko
2020-08-05 16:50 ` Sowjanya Komatineni
2020-08-05 16:57 ` Dmitry Osipenko
2020-08-05 17:04 ` Sowjanya Komatineni
2020-08-05 17:23 ` Dmitry Osipenko
2020-08-05 17:32 ` Sowjanya Komatineni
2020-08-05 17:29 ` Sowjanya Komatineni
2020-08-05 17:34 ` Dmitry Osipenko
2020-08-05 17:46 ` Sowjanya Komatineni
2020-08-05 18:06 ` Sowjanya Komatineni
2020-08-06 0:47 ` Sowjanya Komatineni
2020-08-06 13:32 ` Dmitry Osipenko
2020-08-06 15:59 ` Sowjanya Komatineni
2020-08-06 16:10 ` Dmitry Osipenko
2020-08-06 16:41 ` Sowjanya Komatineni
2020-08-06 16:45 ` Dmitry Osipenko
2020-08-06 16:51 ` Sowjanya Komatineni
2020-08-06 17:15 ` Dmitry Osipenko
2020-08-06 17:12 ` Sowjanya Komatineni [this message]
2020-08-06 17:27 ` Dmitry Osipenko
2020-08-06 17:44 ` Sowjanya Komatineni
2020-08-06 17:52 ` Sowjanya Komatineni
2020-08-06 18:01 ` Dmitry Osipenko
2020-08-06 18:07 ` Sowjanya Komatineni
2020-08-06 18:18 ` Dmitry Osipenko
2020-08-06 18:44 ` Sowjanya Komatineni
2020-08-06 18:51 ` Sowjanya Komatineni
2020-08-06 16:13 ` Dmitry Osipenko
2020-08-06 16:37 ` Dmitry Osipenko
2020-08-06 16:42 ` Sowjanya Komatineni
2020-08-06 16:43 ` Sowjanya Komatineni
2020-08-03 15:42 ` [PATCH v8 09/10] media: tegra-video: Add CSI MIPI pads calibration Sowjanya Komatineni
2020-08-03 15:42 ` [PATCH v8 10/10] media: tegra-video: Compute settle times based on the clock rate Sowjanya Komatineni
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