Re: [PATCH v3 04/12] media: i2c: max9286: Add support for port regulators

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Jacopo,

On Fri, Dec 16, 2022 at 10:52:51AM +0100, Jacopo Mondi wrote:
> On Thu, Dec 15, 2022 at 01:38:17AM +0200, Laurent Pinchart wrote:
> > From: Thomas Nizan <tnizan@witekio.com>
> >
> > Allow users to use one PoC regulator per port, instead of a global
> > regulator.
> >
> > The properties '^port[0-3]-poc-supply$' in the DT node are used to
> > indicate the regulators for individual ports.
> >
> > Signed-off-by: Thomas Nizan <tnizan@witekio.com>
> > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> > ---
> > Changes since v2:
> >
> > - Adapt to the poc-gpio support
> >
> > Changes since v1:
> >
> > - Use to_index()
> > - Use dev_err_probe()
> > - Fix error path in probe()
> > - Use devm_regulator_get_optional() instead of
> >   devm_regulator_get_exclusive()
> > ---
> >  drivers/media/i2c/max9286.c | 138 ++++++++++++++++++++++++++++++------
> >  1 file changed, 115 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> > index 9c083cf14231..d79077939847 100644
> > --- a/drivers/media/i2c/max9286.c
> > +++ b/drivers/media/i2c/max9286.c
> > @@ -139,6 +139,7 @@
> >  struct max9286_source {
> >  	struct v4l2_subdev *sd;
> >  	struct fwnode_handle *fwnode;
> > +	struct regulator *regulator;
> >  };
> >
> >  struct max9286_asd {
> > @@ -169,6 +170,7 @@ struct max9286_priv {
> >  	u32 init_rev_chan_mv;
> >  	u32 rev_chan_mv;
> >
> > +	bool use_gpio_poc;
> >  	u32 gpio_poc[2];
> >
> >  	struct v4l2_ctrl_handler ctrls;
> > @@ -1088,9 +1090,6 @@ static int max9286_parse_gpios(struct max9286_priv *priv)
> >  	struct device *dev = &priv->client->dev;
> >  	int ret;
> >
> > -	/* GPIO values default to high */
> > -	priv->gpio_state = BIT(0) | BIT(1);
> > -
> >  	/*
> >  	 * Parse the "gpio-poc" vendor property. If the property is not
> >  	 * specified the camera power is controlled by a regulator.
> > @@ -1102,18 +1101,7 @@ static int max9286_parse_gpios(struct max9286_priv *priv)
> >  		 * If gpio lines are not used for the camera power, register
> >  		 * a gpio controller for consumers.
> >  		 */
> > -		ret = max9286_register_gpio(priv);
> > -		if (ret)
> > -			return ret;
> > -
> > -		priv->regulator = devm_regulator_get(dev, "poc");
> > -		if (IS_ERR(priv->regulator)) {
> > -			return dev_err_probe(dev, PTR_ERR(priv->regulator),
> > -					     "Unable to get PoC regulator (%ld)\n",
> > -					     PTR_ERR(priv->regulator));
> > -		}
> > -
> > -		return 0;
> > +		return max9286_register_gpio(priv);
> >  	}
> >
> >  	/* If the property is specified make sure it is well formed. */
> > @@ -1124,21 +1112,75 @@ static int max9286_parse_gpios(struct max9286_priv *priv)
> >  		return -EINVAL;
> >  	}
> >
> > +	priv->use_gpio_poc = true;
> >  	return 0;
> >  }
> >
> > +static int max9286_poc_power_on(struct max9286_priv *priv)
> > +{
> > +	struct max9286_source *source;
> > +	unsigned int enabled = 0;
> > +	int ret;
> > +
> > +	/* Enable the global regulator if available. */
> > +	if (priv->regulator)
> > +		return regulator_enable(priv->regulator);
> > +
> > +	if (priv->use_gpio_poc)
> > +		return max9286_gpio_set(priv, priv->gpio_poc[0],
> > +					!priv->gpio_poc[1]);
> 
> #define GPIO_ACTIVE_HIGH 0
> #define GPIO_ACTIVE_LOW 1
> 
> So negating it is correct
> 
> > +
> > +	/* Otherwise use the per-port regulators. */
> > +	for_each_source(priv, source) {
> > +		ret = regulator_enable(source->regulator);
> > +		if (ret < 0)
> > +			goto error;
> > +
> > +		enabled |= BIT(to_index(priv, source));
> > +	}
> > +
> > +	return 0;
> > +
> > +error:
> > +	for_each_source(priv, source) {
> > +		if (enabled & BIT(to_index(priv, source)))
> > +			regulator_disable(source->regulator);
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> > +static int max9286_poc_power_off(struct max9286_priv *priv)
> > +{
> > +	struct max9286_source *source;
> > +	int ret = 0;
> > +
> > +	if (priv->regulator)
> > +		return regulator_disable(priv->regulator);
> > +
> > +	if (priv->use_gpio_poc)
> > +		return max9286_gpio_set(priv, priv->gpio_poc[0],
> > +					priv->gpio_poc[1]);
> > +
> > +	for_each_source(priv, source) {
> > +		int err;
> > +
> > +		err = regulator_disable(source->regulator);
> > +		if (!ret)
> 
> Should this be err ?

No, the intent is to capture the first error. It could be written

		if (err && !ret)

but if the !ret condition is true and err == 0, executing ret = err will
be a no-op, so just testing !ret is fine.

> And I wonder if
>                 ret |= regulator_disable(..)
> 
> isn't enough

If multiple regulator_disable() calls fail with different errors, ret
will be garbage.

> > +			ret = err;
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> >  static int max9286_poc_enable(struct max9286_priv *priv, bool enable)
> >  {
> >  	int ret;
> >
> > -	/* If the regulator is not available, use gpio to control power. */
> > -	if (!priv->regulator)
> > -		ret = max9286_gpio_set(priv, priv->gpio_poc[0],
> > -				       enable ^ priv->gpio_poc[1]);
> > -	else if (enable)
> > -		ret = regulator_enable(priv->regulator);
> > +	if (enable)
> > +		ret = max9286_poc_power_on(priv);
> >  	else
> > -		ret = regulator_disable(priv->regulator);
> > +		ret = max9286_poc_power_off(priv);
> >
> >  	if (ret < 0)
> >  		dev_err(&priv->client->dev, "Unable to turn power %s\n",
> > @@ -1317,6 +1359,47 @@ static int max9286_parse_dt(struct max9286_priv *priv)
> >  	return 0;
> >  }
> >
> > +static int max9286_get_poc_supplies(struct max9286_priv *priv)
> > +{
> > +	struct device *dev = &priv->client->dev;
> > +	struct max9286_source *source;
> > +	int ret;
> > +
> > +	/* Start by getting the global regulator. */
> > +	priv->regulator = devm_regulator_get_optional(dev, "poc");
> > +	if (!IS_ERR(priv->regulator))
> > +		return 0;
> > +
> > +	if (PTR_ERR(priv->regulator) != -ENODEV) {
> > +		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);
> 
> Could this be dev_err_probe ? Or you want to avoid the dev_dbg message ?

Good point, I'll fix that.

> > +	}
> > +
> > +	/* If there's no global regulator, get per-port regulators. */
> > +	dev_dbg(dev,
> > +		"No global PoC regulator, looking for per-port regulators\n");
> > +	priv->regulator = NULL;
> > +
> > +	for_each_source(priv, source) {
> > +		unsigned int index = to_index(priv, source);
> > +		char name[10];
> 
> Will overflow with index > 9 ? But I don't think we can have more than
> 9 ports ?

We're limited to 4 sources (MAX9286_NUM_GMSL is 4), so it should be
fine.

> > +
> > +		snprintf(name, sizeof(name), "port%u-poc", index);
> > +		source->regulator = devm_regulator_get(dev, name);
> > +		if (IS_ERR(source->regulator)) {
> > +			ret = PTR_ERR(source->regulator);
> > +			dev_err_probe(dev, ret,
> > +				      "Unable to get port %u PoC regulator\n",
> > +				      index);
> > +			return ret;
> > +		}
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >  static int max9286_probe(struct i2c_client *client)
> >  {
> >  	struct max9286_priv *priv;
> > @@ -1330,6 +1413,9 @@ static int max9286_probe(struct i2c_client *client)
> >
> >  	priv->client = client;
> >
> > +	/* GPIO values default to high */
> > +	priv->gpio_state = BIT(0) | BIT(1);
> > +
> >  	priv->gpiod_pwdn = devm_gpiod_get_optional(&client->dev, "enable",
> >  						   GPIOD_OUT_HIGH);
> >  	if (IS_ERR(priv->gpiod_pwdn))
> > @@ -1362,7 +1448,13 @@ static int max9286_probe(struct i2c_client *client)
> >
> >  	ret = max9286_parse_dt(priv);
> >  	if (ret)
> > -		goto err_powerdown;
> > +		goto err_cleanup_dt;
> > +
> > +	if (!priv->use_gpio_poc) {
> > +		ret = max9286_get_poc_supplies(priv);
> > +		if (ret)
> > +			goto err_cleanup_dt;
> > +	}
> >
> >  	ret = max9286_init(priv);
> >  	if (ret < 0)
> 
> Do you need to powerdown here ?

I'm not sure to see what's wrong. The error path has

err_cleanup_dt:
	max9286_cleanup_dt(priv);
err_powerdown:
	gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);

	return ret;

-- 
Regards,

Laurent Pinchart