Re: [lm-sensors] [PATCH] hwmon: (lm90) Fix driver to work on standard PCs with CONFIG_REGULATOR enab

[Guenter Roeck <linux@roeck-us.net>]

On 01/26/2014 03:08 PM, Guenter Roeck wrote:
> On Ubuntu systems with CONFIG_REGULATOR enabled, the lm90 driver fails to load
> with an error mesage such as
>
> i2c 1-0018: Driver lm90 requests probe deferral
>
> This is a result of commit 3e0f964f2ad (hwmon: (lm90) Add power control)
> which adds mandatory regulator support to the lm90 driver. On non-dt systems
> with CONFIG_REGULATOR enabled, this fails if regulators are not fully
> specified. This is the case on a standard PC system.
>
Mark appears to object to that idea, so maybe we should just just revert
3e0f964f2ad until a more acceptable solution is found.

Guenter

> To fix the problem, make the regulator on non-dt systems optional.
>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
>   drivers/hwmon/lm90.c |   30 ++++++++++++++++++++----------
>   1 file changed, 20 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
> index bc41682..51932da 100644
> --- a/drivers/hwmon/lm90.c
> +++ b/drivers/hwmon/lm90.c
> @@ -1520,15 +1520,23 @@ static int lm90_probe(struct i2c_client *client,
>   	struct regulator *regulator;
>   	int err;
>
> +	/*
> +	 * On non-dt systems, the regulator subsystem expects regulators
> +	 * to be fully constrained if enabled, which is an unreasonable
> +	 * expectation from the perspective of this driver.
> +	 * Therefore, ignore errors on such systems.
> +	 */
>   	regulator = devm_regulator_get(dev, "vcc");
> -	if (IS_ERR(regulator))
> -		return PTR_ERR(regulator);
> -
> -	err = regulator_enable(regulator);
> -	if (err < 0) {
> -		dev_err(&client->dev,
> -			"Failed to enable regulator: %d\n", err);
> -		return err;
> +	if (IS_ERR(regulator)) {
> +		if (IS_ENABLED(CONFIG_OF))
> +			return PTR_ERR(regulator);
> +	} else {
> +		err = regulator_enable(regulator);
> +		if (err < 0) {
> +			dev_err(&client->dev,
> +				"Failed to enable regulator: %d\n", err);
> +			return err;
> +		}
>   	}
>
>   	data = devm_kzalloc(&client->dev, sizeof(struct lm90_data), GFP_KERNEL);
> @@ -1621,7 +1629,8 @@ exit_remove_files:
>   	lm90_remove_files(client, data);
>   exit_restore:
>   	lm90_restore_conf(client, data);
> -	regulator_disable(data->regulator);
> +	if (!IS_ERR_OR_NULL(data->regulator))
> +		regulator_disable(data->regulator);
>
>   	return err;
>   }
> @@ -1633,7 +1642,8 @@ static int lm90_remove(struct i2c_client *client)
>   	hwmon_device_unregister(data->hwmon_dev);
>   	lm90_remove_files(client, data);
>   	lm90_restore_conf(client, data);
> -	regulator_disable(data->regulator);
> +	if (!IS_ERR_OR_NULL(data->regulator))
> +		regulator_disable(data->regulator);
>
>   	return 0;
>   }
>


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