[bug report] net: pse-pd: Avoid setting max_uA in regulator constraints

[bug report] net: pse-pd: Avoid setting max_uA in regulator constraints

[Dan Carpenter]

Hello Kory Maincent,

Commit 675d0e3cacc3 ("net: pse-pd: Avoid setting max_uA in regulator
constraints") from Jan 10, 2025 (linux-next), leads to the following
Smatch static checker warning:

	drivers/net/pse-pd/pse_core.c:810 pse_pi_set_current_limit()
	warn: AAA no lower bound on 'max_uA' rl='s32min-(-1),1-1920000'

drivers/net/pse-pd/pse_core.c
    783 static int pse_pi_set_current_limit(struct regulator_dev *rdev, int min_uA,
    784                                     int max_uA)
    785 {
    786         struct pse_controller_dev *pcdev = rdev_get_drvdata(rdev);
    787         const struct pse_controller_ops *ops;
    788         int id, mW, ret;
    789         s64 tmp_64;
    790 
    791         ops = pcdev->ops;
    792         if (!ops->pi_set_pw_limit || !ops->pi_get_voltage)
    793                 return -EOPNOTSUPP;
    794 
    795         if (max_uA > MAX_PI_CURRENT)

Do we need this?  Shouldn't it be checked in regulator_check_current_limit()
instead?  max_uA is an int.  Do we need to check for negatives?

    796                 return -ERANGE;
    797 
    798         id = rdev_get_id(rdev);
    799         mutex_lock(&pcdev->lock);
    800         ret = _pse_pi_get_voltage(rdev);
    801         if (!ret) {
    802                 dev_err(pcdev->dev, "Voltage null\n");
    803                 ret = -ERANGE;
    804                 goto out;
    805         }
    806         if (ret < 0)
    807                 goto out;
    808 
    809         tmp_64 = ret;
--> 810         tmp_64 *= max_uA;
    811         /* mW = uA * uV / 1000000000 */
    812         mW = DIV_ROUND_CLOSEST_ULL(tmp_64, 1000000000);
    813         ret = ops->pi_set_pw_limit(pcdev, id, mW);
    814 out:
    815         mutex_unlock(&pcdev->lock);
    816 
    817         return ret;
    818 }

regards,
dan carpenter

Re: [bug report] net: pse-pd: Avoid setting max_uA in regulator constraints

[Kory Maincent]

On Tue, 23 Sep 2025 14:21:03 +0300
Dan Carpenter <dan.carpenter@linaro.org> wrote:

> Hello Kory Maincent,
> 
> Commit 675d0e3cacc3 ("net: pse-pd: Avoid setting max_uA in regulator
> constraints") from Jan 10, 2025 (linux-next), leads to the following
> Smatch static checker warning:
> 
> 	drivers/net/pse-pd/pse_core.c:810 pse_pi_set_current_limit()
> 	warn: AAA no lower bound on 'max_uA' rl='s32min-(-1),1-1920000'
>
> drivers/net/pse-pd/pse_core.c
>     783 static int pse_pi_set_current_limit(struct regulator_dev *rdev, int
> min_uA, 784                                     int max_uA)
>     785 {
>     786         struct pse_controller_dev *pcdev = rdev_get_drvdata(rdev);
>     787         const struct pse_controller_ops *ops;
>     788         int id, mW, ret;
>     789         s64 tmp_64;
>     790 
>     791         ops = pcdev->ops;
>     792         if (!ops->pi_set_pw_limit || !ops->pi_get_voltage)
>     793                 return -EOPNOTSUPP;
>     794 
>     795         if (max_uA > MAX_PI_CURRENT)
> 
> Do we need this?  Shouldn't it be checked in regulator_check_current_limit()
> instead?  max_uA is an int.  Do we need to check for negatives?

No we can't use max_uA in the regulator constraints as I wrote it in the commit
message:
"Setting the max_uA constraint in the regulator API imposes a current
limit during the regulator registration process. This behavior conflicts
with preserving the maximum PI power budget configuration across reboots."

Maybe we need to add a negative check to remove this smatch warning.

Regards,
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com