linux-kernel - Re: [PATCH 4/5] media: mt9p031: Make pixel clock polarity configurable by DT

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Date:   Fri, 25 Sep 2020 23:07:41 +0300
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Stefan Riedmueller <s.riedmueller@...tec.de>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Christian Hemp <c.hemp@...tec.de>
Subject: Re: [PATCH 4/5] media: mt9p031: Make pixel clock polarity
 configurable by DT

Hi Stefan,

Thanks for the patchset.

On Fri, Sep 25, 2020 at 09:50:28AM +0200, Stefan Riedmueller wrote:
> From: Christian Hemp <c.hemp@...tec.de>
> 
> Evaluate the desired pixel clock polarity from the device tree.
> 
> Signed-off-by: Christian Hemp <c.hemp@...tec.de>
> Signed-off-by: Stefan Riedmueller <s.riedmueller@...tec.de>
> ---
>  drivers/media/i2c/Kconfig   |  1 +
>  drivers/media/i2c/mt9p031.c | 19 ++++++++++++++++++-
>  include/media/i2c/mt9p031.h |  1 +
>  3 files changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index c7ba76fee599..7c026daeacf0 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -1103,6 +1103,7 @@ config VIDEO_MT9P031
>  	select MEDIA_CONTROLLER
>  	select VIDEO_V4L2_SUBDEV_API
>  	select VIDEO_APTINA_PLL
> +	select V4L2_FWNODE
>  	help
>  	  This is a Video4Linux2 sensor driver for the Aptina
>  	  (Micron) mt9p031 5 Mpixel camera.
> diff --git a/drivers/media/i2c/mt9p031.c b/drivers/media/i2c/mt9p031.c
> index f5d6a7890c47..8f8ee37a2dd2 100644
> --- a/drivers/media/i2c/mt9p031.c
> +++ b/drivers/media/i2c/mt9p031.c
> @@ -27,6 +27,7 @@
>  #include <media/v4l2-async.h>
>  #include <media/v4l2-ctrls.h>
>  #include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
>  #include <media/v4l2-subdev.h>
>  
>  #include "aptina-pll.h"
> @@ -399,6 +400,14 @@ static int __mt9p031_set_power(struct mt9p031 *mt9p031, bool on)
>  		return ret;
>  	}
>  
> +	/* Configure the pixel clock polarity */
> +	if (mt9p031->pdata && mt9p031->pdata->pixclk_pol) {
> +		ret = mt9p031_write(client, MT9P031_PIXEL_CLOCK_CONTROL,
> +				MT9P031_PIXEL_CLOCK_INVERT);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
>  	return v4l2_ctrl_handler_setup(&mt9p031->ctrls);
>  }
>  
> @@ -1062,7 +1071,8 @@ static const struct v4l2_subdev_internal_ops mt9p031_subdev_internal_ops = {
>  static struct mt9p031_platform_data *
>  mt9p031_get_pdata(struct i2c_client *client)
>  {
> -	struct mt9p031_platform_data *pdata;
> +	struct mt9p031_platform_data *pdata = NULL;
> +	struct v4l2_fwnode_endpoint endpoint;

Could you initialise the bus_type field to a valid value? I suppose this
sensor only supports one of them? That way you'll also initialise the rest
of the struct fields to zero.

>  	struct device_node *np;
>  
>  	if (!IS_ENABLED(CONFIG_OF) || !client->dev.of_node)
> @@ -1072,6 +1082,10 @@ mt9p031_get_pdata(struct i2c_client *client)
>  	if (!np)
>  		return NULL;
>  
> +	endpoint.bus_type = V4L2_MBUS_UNKNOWN;
> +	if (v4l2_fwnode_endpoint_parse(of_fwnode_handle(np), &endpoint) < 0)
> +		goto done;
> +
>  	pdata = devm_kzalloc(&client->dev, sizeof(*pdata), GFP_KERNEL);
>  	if (!pdata)
>  		goto done;
> @@ -1079,6 +1093,9 @@ mt9p031_get_pdata(struct i2c_client *client)
>  	of_property_read_u32(np, "input-clock-frequency", &pdata->ext_freq);
>  	of_property_read_u32(np, "pixel-clock-frequency", &pdata->target_freq);
>  
> +	pdata->pixclk_pol = !!(endpoint.bus.parallel.flags &
> +			       V4L2_MBUS_PCLK_SAMPLE_RISING);
> +
>  done:
>  	of_node_put(np);
>  	return pdata;
> diff --git a/include/media/i2c/mt9p031.h b/include/media/i2c/mt9p031.h
> index 7c29c53aa988..f933cd0be8e5 100644
> --- a/include/media/i2c/mt9p031.h
> +++ b/include/media/i2c/mt9p031.h
> @@ -10,6 +10,7 @@ struct v4l2_subdev;
>   * @target_freq: Pixel clock frequency
>   */
>  struct mt9p031_platform_data {
> +	unsigned int pixclk_pol:1;
>  	int ext_freq;
>  	int target_freq;
>  };

-- 
Regards,

Sakari Ailus