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hwmon: (gpd-fan) Reject EC PWM value 0 as invalid

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The EC firmware is expected to return values in [1, pwm_max]. A read of 0
is illegal and would cause underflow in the conversion formula. Explicitly
check for 0 and return -EIO.

Signed-off-by: Pei Xiao <xiaopei01@kylinos.cn>
Link: https://lore.kernel.org/r/1c2ffa0d832ae3a74f6d4ffa7cc7b7e6cced69e3.1781138459.git.xiaopei01@kylinos.cn
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Pei Xiao 2026-06-11 08:44:14 +08:00 committed by Guenter Roeck
parent 5a1aba28f6
commit 69cbfd7088
1 changed files with 4 additions and 0 deletions
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4
drivers/hwmon/gpd-fan.c
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@ -341,6 +341,10 @@ static int gpd_wm2_read_pwm(struct gpd_fan_data *data)
gpd_ecram_read(drvdata, drvdata->pwm_write, &var);
// EC PWM register valid range is 1 ~ pwm_max; 0 is an invalid state
if (unlikely(!var))
return -EIO;
// Match gpd_generic_write_pwm(u8) below
return DIV_ROUND_CLOSEST((var - 1) * 255, (drvdata->pwm_max - 1));
}