From: sashiko-bot@kernel.org
To: "Rosen Penev" <rosenp@gmail.com>
Cc: linux-hwmon@vger.kernel.org
Subject: Re: [PATCH 1/2] hwmon: (dell-smm) Clamp the pwm value before scaling it
Date: Sat, 14 Nov 2026 06:24:52 +0000 [thread overview]
Message-ID: <sashiko-outbox-214217@kernel.org> (raw)
In-Reply-To: <3c36959a51788bbc5d08f364fe7d922b5c4d4d87.1794633179.git.rosenp@gmail.com>
> dell_smm_write() scales the value written to pwmN with
>
> DIV_ROUND_CLOSEST(val, data->i8k_pwm_mult)
>
> before clamping the result to the valid fan states. The rounding adds
> i8k_pwm_mult / 2 to val first, which overflows for values near
> LONG_MAX and wraps to a large negative number. That is then clamped to
> 0, so writing a huge value turns the fan off instead of running it at
> the highest speed. With the default fan_max of 2, writing any value
> from LONG_MAX - 63 up to LONG_MAX selects fan state 0.
>
> Clamp val to the pwm range of 0 to 255 first.
>
> Fixes: e7f5f275c62a ("i8k: Implement hwmon based fan speed control")
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/cover.1794633179.git.rosenp@gmail.com?part=1
next prev parent reply other threads:[~2026-11-14 6:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-14 6:20 [PATCH 0/2] hwmon: (dell-smm) Validate pwm and fan_max values Rosen Penev
2026-11-14 6:20 ` [PATCH 1/2] hwmon: (dell-smm) Clamp the pwm value before scaling it Rosen Penev
2026-11-14 6:24 ` sashiko-bot [this message]
2026-11-14 6:20 ` [PATCH 2/2] hwmon: (dell-smm) Reject a fan_max that the BIOS cannot take Rosen Penev
2026-11-14 6:25 ` sashiko-bot
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