Re: [hwmon PATCH v3 4/6] hwmon: (adt7470) Fix swapped PWM3 and PWM4 auto mode masks
Guenter Roeck <[email protected]>
| Newsgroups | org.kernel.vger.linux-hwmon,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
On 7/26/26 20:34, Luiz Angelo Daros de Luca wrote: > The ADT7470_PWM3_AUTO_MASK and ADT7470_PWM4_AUTO_MASK macros are > currently defined with swapped bit values. > > According to Table 22 of the ADT7470 datasheet, the Fan Control Mode > Configuration for register 0x69 follows the exact same bit position > layout as register 0x68: > - 0x68 Bit[7] corresponds to BHVR1 (PWM1) -> 0x80 > - 0x68 Bit[6] corresponds to BHVR2 (PWM2) -> 0x40 > - 0x69 Bit[7] corresponds to BHVR3 (PWM3) -> 0x80 > - 0x69 Bit[6] corresponds to BHVR4 (PWM4) -> 0x40 > > Consequently, PWM3 should use mask 0x80 and PWM4 should use 0x40. > > This typo did not cause any functional bugs because these specific > macros are never referenced in the driver code. Instead, the driver > correctly applies the configuration by relying on the modulo parity of > the channel index (e.g., `channel % 2`) to selectively apply either > ADT7470_PWM1_AUTO_MASK (0x80) or ADT7470_PWM2_AUTO_MASK (0x40). > Since the bit layout is identical between the two configuration > registers, the hardware is currently configured correctly. > > Fix the macro definitions to reflect the datasheet accurately and > prevent future bugs or confusion during code review and refactoring. > As this is a purely cosmetic fix with no functional impact, a backport > to stable kernels is not necessary. > If the masks are unused, how about just dropping the definitions instead (including the unused ADT7470_REG_PWM12_CFG and ADT7470_REG_PWM34_CFG) ? That could be done as first patch of the series. Thanks, Guenter