Re: [PATCH v2 01/11] hwmon: (amc6821) Stop accepting invalid pwm values

Quentin Schulz
2024-07-03T14:29:19Z

Hi Guenter,

On 7/1/24 11:23 PM, Guenter Roeck wrote:
> The pwm value range is well defined from 0..255. Don't accept
> any values outside this range.
>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
> v2: Use kstrtou8() instead of kstrtol() where possible.
> Limit range of pwm1_auto_point_pwm to 0..254 in patch 1
> instead of limiting it later, and do not accept invalid
> values for the attribute.
>
> drivers/hwmon/amc6821.c | 15 +++++++++------
> 1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hwmon/amc6821.c b/drivers/hwmon/amc6821.c
> index 9b02b304c2f5..eb2d5592a41a 100644
> --- a/drivers/hwmon/amc6821.c
> +++ b/drivers/hwmon/amc6821.c
> @@ -355,13 +355,13 @@ static ssize_t pwm1_store(struct device *dev,
> {
> struct amc6821_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> - long val;
> - int ret = kstrtol(buf, 10, &val);
> + u8 val;
> + int ret = kstrtou8(buf, 10, &val);
> if (ret)
> return ret;
>
> mutex_lock(&data->update_lock);
> - data->pwm1 = clamp_val(val , 0, 255);
> + data->pwm1 = val;
> i2c_smbus_write_byte_data(client, AMC6821_REG_DCY, data->pwm1);
> mutex_unlock(&data->update_lock);
> return count;
> @@ -558,13 +558,16 @@ static ssize_t pwm1_auto_point_pwm_store(struct device *dev,
> struct amc6821_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> int dpwm;
> - long val;
> - int ret = kstrtol(buf, 10, &val);
> + u8 val;
> + int ret = kstrtou8(buf, 10, &val);
> if (ret)
> return ret;
>
> + if (val > 254)

Would have appreciated a comment as to why it's 254. My understanding is
that the subsystem requires no overlap between multiple pwm_auto_points?
0 being 0 and 2 being 255, we need 1 to be 255?

Actually, that doesn't explain why we allow 0 here, so maybe I'm just
clueless :)

The change itself though:
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>

Thanks!
Quentin