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Date:   Thu, 15 Apr 2021 03:00:56 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Jacopo Mondi <jacopo+renesas@jmondi.org>
Cc:     Geert Uytterhoeven <geert+renesas@glider.be>,
        Magnus Damm <magnus.damm@gmail.com>,
        Kieran Bingham <kieran.bingham@ideasonboard.com>,
        Rob Herring <robh+dt@kernel.org>,
        linux-renesas-soc@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/5] media: i2c: max9286: Use "maxim,gpio-poc" property
Message-ID: <YHeCOCkn1YvYR09E@pendragon.ideasonboard.com>
References: <20210414135128.180980-1-jacopo+renesas@jmondi.org>
 <20210414135128.180980-3-jacopo+renesas@jmondi.org>
MIME-Version: 1.0
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In-Reply-To: <20210414135128.180980-3-jacopo+renesas@jmondi.org>
Precedence: bulk

Hi Jacopo,

Thank you for the patch.

On Wed, Apr 14, 2021 at 03:51:25PM +0200, Jacopo Mondi wrote:
> The 'maxim,gpio-poc' property is used when the remote camera
> power-over-coax is controlled by one of the MAX9286 gpio lines,
> to instruct the driver about which line to use and what the line
> polarity is.
> 
> Add to the max9286 driver support for parsing the newly introduce
s/introduce/introduced/

> property and use it if available in place of the usual supply, as it is
> not possible to establish one as consumer of the max9286 gpio
> controller.
> 
> If the new property is present, no gpio controller is registered and
> 'poc-supply' is ignored.
> 
> In order to maximize code re-use, break out the max9286 gpio handling
> function so that they can be used by the gpio controller through the
> gpio-consumer API, or directly by the driver code.
> 
> Wrap the power up and power down routines to their own function to
> be able to use either the gpio line directly or the supply. This will
> make it easier to control the remote camera power at run time.

I would have split the patch in two, with a first patch that refactors
the code, and a second one that extends it, but that's no big deal.

> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> ---
>  drivers/media/i2c/max9286.c | 125 +++++++++++++++++++++++++++---------
>  1 file changed, 96 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> index 6fd4d59fcc72..0c125f7b3d9b 100644
> --- a/drivers/media/i2c/max9286.c
> +++ b/drivers/media/i2c/max9286.c
> @@ -15,6 +15,7 @@
>  #include <linux/fwnode.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/gpio/driver.h>
> +#include <linux/gpio/machine.h>
>  #include <linux/i2c.h>
>  #include <linux/i2c-mux.h>
>  #include <linux/module.h>
> @@ -165,6 +166,9 @@ struct max9286_priv {
>  
>  	u32 reverse_channel_mv;
>  
> +	u32 gpio_poc;
> +	u32 gpio_poc_flags;
> +
>  	struct v4l2_ctrl_handler ctrls;
>  	struct v4l2_ctrl *pixelrate;
>  
> @@ -1022,20 +1026,27 @@ static int max9286_setup(struct max9286_priv *priv)
>  	return 0;
>  }
>  
> -static void max9286_gpio_set(struct gpio_chip *chip,
> -			     unsigned int offset, int value)
> +static int max9286_gpio_set(struct max9286_priv *priv, unsigned int offset,
> +			    int value)
>  {
> -	struct max9286_priv *priv = gpiochip_get_data(chip);
> -
>  	if (value)
>  		priv->gpio_state |= BIT(offset);
>  	else
>  		priv->gpio_state &= ~BIT(offset);
>  
> -	max9286_write(priv, 0x0f, MAX9286_0X0F_RESERVED | priv->gpio_state);
> +	return max9286_write(priv, 0x0f,
> +			     MAX9286_0X0F_RESERVED | priv->gpio_state);
> +}
> +
> +static void max9286_gpiochip_set(struct gpio_chip *chip,
> +				 unsigned int offset, int value)
> +{
> +	struct max9286_priv *priv = gpiochip_get_data(chip);
> +
> +	max9286_gpio_set(priv, offset, value);
>  }
>  
> -static int max9286_gpio_get(struct gpio_chip *chip, unsigned int offset)
> +static int max9286_gpiochip_get(struct gpio_chip *chip, unsigned int offset)
>  {
>  	struct max9286_priv *priv = gpiochip_get_data(chip);
>  
> @@ -1055,8 +1066,8 @@ static int max9286_register_gpio(struct max9286_priv *priv)
>  	gpio->of_node = dev->of_node;
>  	gpio->ngpio = 2;
>  	gpio->base = -1;
> -	gpio->set = max9286_gpio_set;
> -	gpio->get = max9286_gpio_get;
> +	gpio->set = max9286_gpiochip_set;
> +	gpio->get = max9286_gpiochip_get;
>  	gpio->can_sleep = true;
>  
>  	/* GPIO values default to high */
> @@ -1069,6 +1080,75 @@ static int max9286_register_gpio(struct max9286_priv *priv)
>  	return ret;
>  }
>  
> +static int max9286_parse_gpios(struct max9286_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	u32 gpio_poc[2];
> +	int ret;
> +
> +	/*
> +	 * Parse the "gpio-poc" vendor property. If the camera power is
> +	 * controlled by one of the MAX9286 gpio lines, do not register
> +	 * the gpio controller and ignore 'poc-supply'.
> +	 */
> +	ret = of_property_read_u32_array(dev->of_node,
> +					 "maxim,gpio-poc", gpio_poc, 2);
> +	if (!ret) {
> +		priv->gpio_poc = gpio_poc[0];
> +		priv->gpio_poc_flags = gpio_poc[1];
> +		if ((priv->gpio_poc != 0 && priv->gpio_poc != 1) ||

You could simply test priv->gpio_poc > 1.

> +		    (priv->gpio_poc_flags != GPIO_ACTIVE_HIGH &&
> +		     priv->gpio_poc_flags != GPIO_ACTIVE_LOW)) {
> +			dev_err(dev, "Invalid 'gpio-poc': (%u %u)\n",
> +				priv->gpio_poc, priv->gpio_poc_flags);
> +			return -EINVAL;
> +		}
> +
> +		/* GPIO values default to high */
> +		priv->gpio_state = BIT(0) | BIT(1);

Why is that ?

> +		priv->regulator = NULL;

As priv is initialized to 0, you can skip this.

> +
> +		return 0;
> +	}
> +
> +	ret = max9286_register_gpio(priv);
> +	if (ret)
> +		return ret;
> +
> +	priv->regulator = devm_regulator_get(dev, "poc");
> +	if (IS_ERR(priv->regulator)) {
> +		if (PTR_ERR(priv->regulator) != -EPROBE_DEFER)
> +			dev_err(dev, "Unable to get PoC regulator (%ld)\n",
> +				PTR_ERR(priv->regulator));
> +		return PTR_ERR(priv->regulator);
> +	}
> +
> +	return 0;
> +}
> +
> +static int max9286_poc_enable(struct max9286_priv *priv, bool enable)
> +{
> +	int ret;
> +
> +	/* If "poc-gpio" is used, toggle the line and do not use regulator. */
> +	if (!priv->regulator)
> +		return max9286_gpio_set(priv, priv->gpio_poc,
> +					enable ^ priv->gpio_poc_flags);
> +
> +	/* Otherwise PoC is controlled using a regulator. */
> +	if (enable) {
> +		ret = regulator_enable(priv->regulator);
> +		if (ret < 0) {
> +			dev_err(&priv->client->dev, "Unable to turn PoC on\n");

As error message when max9286_gpio_set() fails (at least in the enable
case) would be good too. Bonus points if there's a single dev_err()
call.

> +			return ret;
> +		}
> +
> +		return 0;
> +	}
> +
> +	return regulator_disable(priv->regulator);
> +}
> +
>  static int max9286_init(struct device *dev)
>  {
>  	struct max9286_priv *priv;
> @@ -1078,17 +1158,14 @@ static int max9286_init(struct device *dev)
>  	client = to_i2c_client(dev);
>  	priv = i2c_get_clientdata(client);
>  
> -	/* Enable the bus power. */
> -	ret = regulator_enable(priv->regulator);
> -	if (ret < 0) {
> -		dev_err(&client->dev, "Unable to turn PoC on\n");
> +	ret = max9286_poc_enable(priv, true);
> +	if (ret)
>  		return ret;
> -	}
>  
>  	ret = max9286_setup(priv);
>  	if (ret) {
>  		dev_err(dev, "Unable to setup max9286\n");
> -		goto err_regulator;
> +		goto err_poc_disable;
>  	}
>  
>  	/*
> @@ -1098,7 +1175,7 @@ static int max9286_init(struct device *dev)
>  	ret = max9286_v4l2_register(priv);
>  	if (ret) {
>  		dev_err(dev, "Failed to register with V4L2\n");
> -		goto err_regulator;
> +		goto err_poc_disable;
>  	}
>  
>  	ret = max9286_i2c_mux_init(priv);
> @@ -1114,8 +1191,8 @@ static int max9286_init(struct device *dev)
>  
>  err_v4l2_register:
>  	max9286_v4l2_unregister(priv);
> -err_regulator:
> -	regulator_disable(priv->regulator);
> +err_poc_disable:
> +	max9286_poc_enable(priv, false);
>  
>  	return ret;
>  }
> @@ -1286,20 +1363,10 @@ static int max9286_probe(struct i2c_client *client)
>  	 */
>  	max9286_configure_i2c(priv, false);
>  
> -	ret = max9286_register_gpio(priv);
> +	ret = max9286_parse_gpios(priv);
>  	if (ret)
>  		goto err_powerdown;
>  
> -	priv->regulator = devm_regulator_get(&client->dev, "poc");
> -	if (IS_ERR(priv->regulator)) {
> -		if (PTR_ERR(priv->regulator) != -EPROBE_DEFER)
> -			dev_err(&client->dev,
> -				"Unable to get PoC regulator (%ld)\n",
> -				PTR_ERR(priv->regulator));
> -		ret = PTR_ERR(priv->regulator);
> -		goto err_powerdown;
> -	}
> -
>  	ret = max9286_parse_dt(priv);
>  	if (ret)
>  		goto err_powerdown;
> @@ -1326,7 +1393,7 @@ static int max9286_remove(struct i2c_client *client)
>  
>  	max9286_v4l2_unregister(priv);
>  
> -	regulator_disable(priv->regulator);
> +	max9286_poc_enable(priv, false);
>  
>  	gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);
>  

-- 
Regards,

Laurent Pinchart