linux-kernel - Re: [RFC PATCH v5 13/14] media: tegra-video: Add CSI MIPI pads calibration

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Date:   Tue, 28 Jul 2020 13:30:46 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>,
        thierry.reding@...il.com, jonathanh@...dia.com, frankc@...dia.com,
        hverkuil@...all.nl, sakari.ailus@....fi, robh+dt@...nel.org,
        helen.koike@...labora.com
Cc:     sboyd@...nel.org, gregkh@...uxfoundation.org,
        linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-i2c@...r.kernel.org
Subject: Re: [RFC PATCH v5 13/14] media: tegra-video: Add CSI MIPI pads
 calibration

27.07.2020 23:57, Sowjanya Komatineni пишет:
> +	/*
> +	 * TRM has incorrectly documented to wait for done status from
> +	 * calibration logic after CSI interface power on.
> +	 * As per the design, calibration results are latched and applied
> +	 * to the pads only when the link is in LP11 state which will happen
> +	 * during the sensor stream-on.
> +	 * CSI subdev stream-on triggers start of MIPI pads calibration.
> +	 * Wait for calibration to finish here after sensor subdev stream-on
> +	 * and in case of sensor stream-on failure, cancel the calibration.
> +	 */
>  	subdev = on ? src_subdev : csi_subdev;
>  	ret = v4l2_subdev_call(subdev, video, s_stream, on);
> -	if (ret < 0 && ret != -ENOIOCTLCMD)
> +	if (ret < 0 && ret != -ENOIOCTLCMD) {

I assume -ENOIOCTLCMD means that camera wasn't turned ON, so why
-ENOIOCTLCMD is special?

> +		if (on && csi_chan->mipi)
> +			tegra_mipi_cancel_calibration(csi_chan->mipi);
>  		return ret;
> +	}
> +
> +	if (on && csi_chan->mipi) {

Does finish_calibration() really need to be called for ret=-ENOIOCTLCMD?

Shouldn't it be cancel_calibration( for the -ENOIOCTLCMD?

> +		ret = tegra_mipi_finish_calibration(csi_chan->mipi);
> +		if (ret < 0)
> +			dev_err(csi_chan->csi->dev,
> +				"MIPI calibration failed: %d\n", ret);

Doesn't v4l2_subdev_call(OFF) need to be invoked here on error?

> +		return ret;
> +	}
>  
>  	return 0;
>  }