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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 v6 09/10] media: tegra-video: Add CSI MIPI pads calibration
Date: Fri, 31 Jul 2020 09:29:00 -0700
Message-ID: <ace047fe-8a1a-666a-b91b-9d63b1d68567@nvidia.com> (raw)
In-Reply-To: <a08af0e8-80d8-0bd0-87a3-adfc8e70a92a@gmail.com>


On 7/31/20 9:14 AM, Dmitry Osipenko wrote:
> 31.07.2020 18:46, Sowjanya Komatineni пишет:
>> On 7/31/20 4:39 AM, Dmitry Osipenko wrote:
>>> 31.07.2020 12:02, Sowjanya Komatineni пишет:
>>> ...
>>>> @@ -249,13 +249,47 @@ static int tegra_csi_enable_stream(struct
>>>> v4l2_subdev *subdev)
>>>>            return ret;
>>>>        }
>>>>    +    if (csi_chan->mipi) {
>>>> +        ret = tegra_mipi_enable(csi_chan->mipi);
>>>> +        if (ret < 0) {
>>>> +            dev_err(csi->dev,
>>>> +                "failed to enable MIPI pads: %d\n", ret);
>>>> +            goto rpm_put;
>>>> +        }
>>>> +
>>>> +        /*
>>>> +         * CSI MIPI pads PULLUP, PULLDN and TERM impedances need to
>>>> +         * be calibrated after power on.
>>>> +         * So, trigger the calibration start here and results will
>>>> +         * be latched and applied to the pads when link is in LP11
>>>> +         * state during start of sensor streaming.
>>>> +         */
>>>> +        ret = tegra_mipi_start_calibration(csi_chan->mipi);
>>>> +        if (ret < 0) {
>>>> +            dev_err(csi->dev,
>>>> +                "failed to start MIPI calibration: %d\n", ret);
>>>> +            goto disable_mipi;
>>>> +        }
>>> What would happen if CSI stream is enabled and then immediately disabled
>>> without enabling camera sensor?
>> Nothing will happen as during stream enable csi receiver is kept ready.
>>
>> But actual capture will not happen during that point.
> Could you please show how the full call chain looks like? It's not clear
> to me what keeps CSI stream "ready".

VI is the main video input (video device) and on streaming it starts 
stream of CSI subdev prior to stream of Sensor.

HW path, sensor stream (CSI TX) -> CSI stream (RX)

During CSI stream on, CSI PHY receiver is enabled to start receiving the 
data but internally capture assembled to active state will happen only 
when Tegra VI single shot is issues where VI thru pixel parser gets 
captures data into the memory



  reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-31  9:02 [RFC PATCH v6 00/10] Support for Tegra video capture from external sensor Sowjanya Komatineni
2020-07-31  9:02 ` [RFC PATCH v6 01/10] media: tegra-video: Fix channel format alignment Sowjanya Komatineni
2020-07-31  9:02 ` [RFC PATCH v6 02/10] media: tegra-video: Enable TPG based on kernel config Sowjanya Komatineni
2020-07-31  9:02 ` [RFC PATCH v6 03/10] media: tegra-video: Update format lookup to offset based Sowjanya Komatineni
2020-07-31  9:02 ` [RFC PATCH v6 04/10] dt-bindings: tegra: Update VI and CSI bindings with port info Sowjanya Komatineni
2020-07-31  9:02 ` [RFC PATCH v6 05/10] media: tegra-video: Separate CSI stream enable and disable implementations Sowjanya Komatineni
2020-07-31 12:06   ` Dmitry Osipenko
2020-07-31  9:02 ` [RFC PATCH v6 06/10] media: tegra-video: Add support for external sensor capture Sowjanya Komatineni
2020-07-31  9:02 ` [RFC PATCH v6 07/10] media: tegra-video: Add support for selection ioctl ops Sowjanya Komatineni
2020-07-31  9:02 ` [RFC PATCH v6 08/10] gpu: host1x: mipi: Keep MIPI clock enabled till calibration is done Sowjanya Komatineni
2020-07-31  9:02 ` [RFC PATCH v6 09/10] media: tegra-video: Add CSI MIPI pads calibration Sowjanya Komatineni
2020-07-31 11:39   ` Dmitry Osipenko
2020-07-31 15:46     ` Sowjanya Komatineni
2020-07-31 16:14       ` Dmitry Osipenko
2020-07-31 16:29         ` Sowjanya Komatineni [this message]
2020-07-31  9:02 ` [RFC PATCH v6 10/10] media: tegra-video: Compute settle times based on the clock rate Sowjanya Komatineni
2020-07-31 13:40 ` [RFC PATCH v6 00/10] Support for Tegra video capture from external sensor Wolfram Sang
2020-07-31 15:49   ` Sowjanya Komatineni

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