Re: [PATCH v2 4/6] hwmon: (lm63) Add Sensylink CTF2301 support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Unchecked I2C reads for LSB are bitwise-ORed into 16-bit register values, corrupting data on read errors.
--

--- Patch [4]: [PATCH v2 4/6] hwmon: (lm63) Add Sensylink CTF2301 support ---
commit bbf54143e45eb1b3b9599d60a55904a5184333c9
Author: Troy Mitchell <troy.mitchell@linux.dev>

hwmon: (lm63) Add Sensylink CTF2301 support

This commit adds support for the Sensylink CTF2301 chip to the lm63 driver.
It introduces extended local temperature resolution and optional thermal
cooling device registration.

> diff --git a/drivers/hwmon/lm63.c b/drivers/hwmon/lm63.c
> index e2a429e579ac1..764a7467afa60 100644
> --- a/drivers/hwmon/lm63.c
> +++ b/drivers/hwmon/lm63.c

[ ... ]

> @@ -256,8 +270,16 @@ static struct lm63_data *lm63_update_device(struct device *dev)
>  
>  		data->temp8[0] = i2c_smbus_read_byte_data(client,
>  				 LM63_REG_LOCAL_TEMP);
> +		if (data->kind == ctf2301)
> +			data->temp1_input = ((u16)(u8)data->temp8[0] << 8)
> +					  | i2c_smbus_read_byte_data(client,
> +						CTF2301_REG_LOCAL_TEMP_LSB);
>  		data->temp8[1] = i2c_smbus_read_byte_data(client,
>  				 LM63_REG_LOCAL_HIGH);
> +		if (data->kind == ctf2301)
> +			data->temp1_max = ((u16)(u8)data->temp8[1] << 8)
> +					  | i2c_smbus_read_byte_data(client,
> +						CTF2301_REG_LOCAL_HIGH_LSB);

[Severity: Medium]
Will this corrupt the temperature reading if the I2C read fails?

In lm63_update_device(), if i2c_smbus_read_byte_data() for the LSB returns
a negative error code (such as -EIO), it gets bitwise-ORed with the shifted
MSB. The negative s32 error code would sign-extend, overwriting the MSB
bits entirely and resulting in a large negative temperature spike instead
of propagating the error or maintaining the previous valid reading.

Could we check the return value of i2c_smbus_read_byte_data() before
merging it into temp1_input and temp1_max?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260721-ctl2301-v2-0-ef5fb342872a@linux.dev?part=4