From: Guenter Roeck <linux@roeck-us.net>
To: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>,
Andrew Morton <akpm@linux-foundation.org>,
"Darrick J. Wong" <djwong@us.ibm.com>,
"Mark M. Hoffman" <mhoffman@lightlink.com>,
linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [hwmon PATCH v2 4/8] hwmon: (adt7470) Fix swapped PWM3 and PWM4 auto mode masks
Date: Mon, 27 Jul 2026 17:57:03 -0700 [thread overview]
Message-ID: <5ce1a42b-91ac-4fba-9153-34dc8de76a04@roeck-us.net> (raw)
In-Reply-To: <20260727-adt7470_fixes-v2-4-598e38a46ba6@gmail.com>
On Mon, Jul 27, 2026 at 09:22:20PM -0300, 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.
>
> Fixes: 6f9703d0be16 ("hwmon: add support for adt7470")
> Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Applied.
Thanks,
Guenter
next prev parent reply other threads:[~2026-07-28 0:57 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-28 0:22 [hwmon PATCH v2 0/8] hwmon: (adt7470): Multiple fixes Luiz Angelo Daros de Luca
2026-07-28 0:22 ` [hwmon PATCH v2 1/8] hwmon: (adt7470) Fix fans stuck in manual mode on I2C errors Luiz Angelo Daros de Luca
2026-07-28 0:53 ` Guenter Roeck
2026-07-28 0:22 ` [hwmon PATCH v2 2/8] hwmon: (adt7470) Fix cache updated before hardware write on I2C error Luiz Angelo Daros de Luca
2026-07-28 0:54 ` Guenter Roeck
2026-07-28 0:22 ` [hwmon PATCH v2 3/8] hwmon: (adt7470) Fix busy-loop and I2C flooding in update thread Luiz Angelo Daros de Luca
2026-07-28 0:55 ` Guenter Roeck
2026-07-28 0:22 ` [hwmon PATCH v2 4/8] hwmon: (adt7470) Fix swapped PWM3 and PWM4 auto mode masks Luiz Angelo Daros de Luca
2026-07-28 0:57 ` Guenter Roeck [this message]
2026-07-28 0:22 ` [hwmon PATCH v2 5/8] hwmon: (adt7470) Fix temperature alarm logic in hwmon_temp_read() Luiz Angelo Daros de Luca
2026-07-28 0:55 ` Guenter Roeck
2026-07-28 0:22 ` [hwmon PATCH v2 6/8] hwmon: (adt7470) Use cached PWM frequency value Luiz Angelo Daros de Luca
2026-07-28 0:57 ` Guenter Roeck
2026-07-28 0:22 ` [hwmon PATCH v2 7/8] hwmon: (adt7470) Fix divide-by-zero TOCTOU crash in fan speed read Luiz Angelo Daros de Luca
2026-07-28 0:58 ` Guenter Roeck
2026-07-28 0:22 ` [hwmon PATCH v2 8/8] hwmon: (adt7470) Fix PWM auto temp state array and bounds check Luiz Angelo Daros de Luca
2026-07-28 0:58 ` Guenter Roeck
2026-07-28 1:04 ` [hwmon PATCH v2 0/8] hwmon: (adt7470): Multiple fixes Guenter Roeck
2026-07-28 1:08 ` Luiz Angelo Daros de Luca
2026-07-28 3:35 ` Guenter Roeck
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