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From: Sowjanya Komatineni <skomatineni@nvidia.com>
To: Dmitry Osipenko <digetx@gmail.com>, <thierry.reding@gmail.com>,
	<jonathanh@nvidia.com>, <frankc@nvidia.com>, <hverkuil@xs4all.nl>,
	<sakari.ailus@iki.fi>, <robh+dt@kernel.org>,
	<helen.koike@collabora.com>
Cc: <sboyd@kernel.org>, <gregkh@linuxfoundation.org>,
	<linux-media@vger.kernel.org>, <devicetree@vger.kernel.org>,
	<linux-tegra@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-i2c@vger.kernel.org>
Subject: Re: [RFC PATCH v5 12/14] gpu: host1x: mipi: Keep MIPI clock enabled till calibration is done
Date: Wed, 29 Jul 2020 16:54:29 -0700
Message-ID: <b159e69a-32fa-7bcb-3c95-aaaba250f85b@nvidia.com> (raw)
In-Reply-To: <48977b6b-ef7e-1bdf-e3e0-2903032aa225@gmail.com>


On 7/29/20 4:42 PM, Dmitry Osipenko wrote:
> 29.07.2020 20:55, Sowjanya Komatineni пишет:
>> On 7/29/20 10:08 AM, Dmitry Osipenko wrote:
>>> 28.07.2020 19:04, Sowjanya Komatineni пишет:
>>> ...
>>>>>> +void tegra_mipi_cancel_calibration(struct tegra_mipi_device *device)
>>>>>> +{
>>>>> Doesn't MIPI_CAL need to be reset here?
>>>> No need to reset MIPI CAL
>>> Could you please explain why. There is a calibration state-machine that
>>> apparently needs to be returned into initial state, does it return by
>>> itself?
>>>
>>> TRM says that MIPI block needs to be reset before of starting
>>> calibration process. The reset is completely missing in the driver, I
>>> assume it needs to be corrected with another patch.
>> TRM documented incorrectly. There is no need to reset MIPI_CAL.
>>
>> MIPI CAL is FSM and it does not hang and done bit is to indicate if
>> results are applied to pads or not.
>>
>> If we don't see done bit set meaning, MIPI CAL did not see LP-11 and
>> results are not applied to pads.
> But how to stop calibration from triggering on LP-11 once it has been
> enabled? The reset should be needed since there is no other way to reset
> the calibration state.

Its a finite state machine that goes thru fixed steps of sequence codes 
internally and holds results in registers.

When it sees LP-11 results are applied to pads.

If it does not see LP-11, next start will again trigger calibrating with 
finite sequence codes.

As per HW designers, we don't have to do any reverts when done bit is 
not set.

>> Also while multiple streams can happen in parallel and we can't reset
>> MIPI CAL as other CSI channel streams (using other pads) may also be
>> going thru calibration process in parallel depending and also DSI pads
>> also are calibrated thru same MIPI CAL controller.
> Perhaps this should be the case for a shared reset control API usage.

  reply index

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-27 20:57 [RFC PATCH v5 00/14] Support for Tegra video capture from external sensor Sowjanya Komatineni
2020-07-27 20:57 ` [RFC PATCH v5 01/14] i2c: tegra: Don't mark VI I2C as IRQ safe runtime PM Sowjanya Komatineni
2020-07-28 16:33   ` Wolfram Sang
2020-07-27 20:57 ` [RFC PATCH v5 02/14] i2c: tegra: Remove NULL pointer check before clk_enable/disable/prepare/unprepare Sowjanya Komatineni
2020-07-28 16:33   ` Wolfram Sang
2020-07-27 20:57 ` [RFC PATCH v5 03/14] i2c: tegra: Fix the error path in tegra_i2c_runtime_resume Sowjanya Komatineni
2020-07-28 16:33   ` Wolfram Sang
2020-07-27 20:57 ` [RFC PATCH v5 04/14] i2c: tegra: Fix runtime resume to re-init VI I2C Sowjanya Komatineni
2020-07-28 16:33   ` Wolfram Sang
2020-07-27 20:57 ` [RFC PATCH v5 05/14] i2c: tegra: Avoid tegra_i2c_init_dma() for Tegra210 vi i2c Sowjanya Komatineni
2020-07-28 16:34   ` Wolfram Sang
2020-07-27 20:57 ` [RFC PATCH v5 06/14] media: tegra-video: Fix channel format alignment Sowjanya Komatineni
2020-07-27 20:57 ` [RFC PATCH v5 07/14] media: tegra-video: Enable TPG based on kernel config Sowjanya Komatineni
2020-07-27 20:57 ` [RFC PATCH v5 08/14] media: tegra-video: Update format lookup to offset based Sowjanya Komatineni
2020-07-27 20:57 ` [RFC PATCH v5 09/14] dt-bindings: tegra: Update VI and CSI bindings with port info Sowjanya Komatineni
2020-07-27 20:57 ` [RFC PATCH v5 10/14] media: tegra-video: Add support for external sensor capture Sowjanya Komatineni
2020-07-27 20:57 ` [RFC PATCH v5 11/14] media: tegra-video: Add support for selection ioctl ops Sowjanya Komatineni
2020-07-27 20:57 ` [RFC PATCH v5 12/14] gpu: host1x: mipi: Keep MIPI clock enabled till calibration is done Sowjanya Komatineni
2020-07-28 11:03   ` Dmitry Osipenko
2020-07-28 16:04     ` Sowjanya Komatineni
2020-07-29 17:08       ` Dmitry Osipenko
2020-07-29 17:55         ` Sowjanya Komatineni
2020-07-29 23:42           ` Dmitry Osipenko
2020-07-29 23:54             ` Sowjanya Komatineni [this message]
2020-07-30  0:31               ` Dmitry Osipenko
2020-07-27 20:57 ` [RFC PATCH v5 13/14] media: tegra-video: Add CSI MIPI pads calibration Sowjanya Komatineni
2020-07-28 10:30   ` Dmitry Osipenko
2020-07-28 15:59     ` Sowjanya Komatineni
2020-07-28 19:43       ` Sowjanya Komatineni
2020-07-29 23:25       ` Dmitry Osipenko
2020-07-29 23:59         ` Sowjanya Komatineni
2020-07-30  0:27           ` Sowjanya Komatineni
2020-07-30  0:43             ` Dmitry Osipenko
2020-07-30  0:52               ` Sowjanya Komatineni
2020-07-30  0:55                 ` Sowjanya Komatineni
2020-07-30  0:53                   ` Dmitry Osipenko
2020-07-30  1:06                     ` Sowjanya Komatineni
2020-07-30  1:10                       ` Dmitry Osipenko
2020-07-30  0:47             ` Sowjanya Komatineni
2020-07-27 20:57 ` [RFC PATCH v5 14/14] media: tegra-video: Compute settle times based on the clock rate Sowjanya Komatineni

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