Re: [PATCH v0 2/2] hwmon: pmbus: Add tps546e25 to generic pmbus

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 4 potential issue(s) to consider:

New issues:
- [Medium] The new `tps546e25` device entry incorrectly uses `pmbus_info_zero` instead of `pmbus_info_one`, which forces unnecessary dynamic page probing.
- [Low] The new compatible string is not documented in the device tree bindings.
- [Low] The new device is missing from the generic PMBus driver documentation.

Pre-existing issues:
- [High] Potential NULL pointer dereference of `device_info` in `pmbus_probe()`.
--

commit fc4eef8dbc6c89c58d89c8feeedc224bbb325745
Author: Aryan Srivastava <aryan.srivastava@alliedtelesis.co.nz>
Subject: hwmon: pmbus: Add tps546e25 to generic pmbus

This commit adds support for the tps546e25 device to the generic PMBus driver.
It operates over SMBus and is similar to other TI DCDC devices.

> diff --git a/drivers/hwmon/pmbus/pmbus.c b/drivers/hwmon/pmbus/pmbus.c
> index b629acbffbfb6..96a72950e7d36 100644
> --- a/drivers/hwmon/pmbus/pmbus.c
> +++ b/drivers/hwmon/pmbus/pmbus.c
> @@ -245,6 +245,7 @@ static const struct i2c_device_id pmbus_id[] = {
>  	{ .name = "tps544b25", .driver_data = (kernel_ulong_t)&pmbus_info_one },
>  	{ .name = "tps544c20", .driver_data = (kernel_ulong_t)&pmbus_info_one },
>  	{ .name = "tps544c25", .driver_data = (kernel_ulong_t)&pmbus_info_one },
> +	{ .name = "tps546e25", .driver_data = (kernel_ulong_t)&pmbus_info_zero },

[Severity: Medium]
Since this is similar to other TI DCDC devices, should this use pmbus_info_one
instead of pmbus_info_zero?

Using pmbus_info_zero forces dynamic page probing, which causes unnecessary
I2C/SMBus traffic. If the device ignores the data but ACKs out-of-range page
writes, it could expose 32 identical phantom pages in sysfs.

>  	{ .name = "udt020", .driver_data = (kernel_ulong_t)&pmbus_info_one },
>  	{ }
>  };


[Severity: Low]
Is it intentional that the new device is omitted from the device tree bindings?

Adding ti,tps546e25 to Documentation/devicetree/bindings/trivial-devices.yaml
would prevent dtbs_check warnings when this compatible string is used.


[Severity: Low]
Could we also update the supported hardware documentation in
Documentation/hwmon/pmbus.rst?

Adding the TPS546E25 to the list of Texas Instruments devices and its prefix
'tps546e25' would ensure users know it is supported by this driver.


[Severity: High]
This is a pre-existing issue, but I noticed a potential NULL pointer dereference
in pmbus_probe().

drivers/hwmon/pmbus/pmbus.c:pmbus_probe() {
    ...
	device_info = (struct pmbus_device_info *)i2c_get_match_data(client);
	if (device_info->flags) {
    ...
}

If the driver is bound manually via sysfs (e.g., using driver_override)
without an I2C ID that matches the driver's id_table, i2c_get_match_data()
will return NULL. The code immediately dereferences device_info->flags,
which will cause a kernel crash.

Does this need to be checked before dereferencing?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260904005351.2136374-1-aryan.srivastava@alliedtelesis.co.nz?part=2