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| author | Guenter Roeck <linux@roeck-us.net> | 2021-05-26 08:40:18 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-07-14 16:55:55 +0200 |
| commit | 625ee7d26799a8219a684d295070bbbc911ed7f4 (patch) | |
| tree | b350e098e5a28c4536aba23b4d2690199b84037b /Documentation/hwmon | |
| parent | c1eb091dbbbb1054892330f14a3d60d6f6d20b93 (diff) | |
| download | linux-stable-625ee7d26799a8219a684d295070bbbc911ed7f4.tar.gz linux-stable-625ee7d26799a8219a684d295070bbbc911ed7f4.tar.bz2 linux-stable-625ee7d26799a8219a684d295070bbbc911ed7f4.zip | |
hwmon: (max31790) Fix pwmX_enable attributes
[ Upstream commit 148c847c9e5a54b99850617bf9c143af9a344f92 ]
pwmX_enable supports three possible values:
0: Fan control disabled. Duty cycle is fixed to 0%
1: Fan control enabled, pwm mode. Duty cycle is determined by
values written into Target Duty Cycle registers.
2: Fan control enabled, rpm mode
Duty cycle is adjusted such that fan speed matches
the values in Target Count registers
The current code does not do this; instead, it mixes pwm control
configuration with fan speed monitoring configuration. Worse, it
reports that pwm control would be disabled (pwmX_enable==0) when
it is in fact enabled in pwm mode. Part of the problem may be that
the chip sets the "TACH input enable" bit on its own whenever the
mode bit is set to RPM mode, but that doesn't mean that "TACH input
enable" accurately reflects the pwm mode.
Fix it up and only handle pwm control with the pwmX_enable attributes.
In the documentation, clarify that disabling pwm control (pwmX_enable=0)
sets the pwm duty cycle to 0%. In the code, explain why TACH_INPUT_EN
is set together with RPM_MODE.
While at it, only update the configuration register if the configuration
has changed, and only update the cached configuration if updating the
chip configuration was successful.
Cc: Jan Kundrát <jan.kundrat@cesnet.cz>
Cc: Václav Kubernát <kubernat@cesnet.cz>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Václav Kubernát <kubernat@cesnet.cz>
Reviewed-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Link: https://lore.kernel.org/r/20210526154022.3223012-4-linux@roeck-us.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'Documentation/hwmon')
| -rw-r--r-- | Documentation/hwmon/max31790.rst | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/Documentation/hwmon/max31790.rst b/Documentation/hwmon/max31790.rst index 54ff0f49e28f..7b097c3b9b90 100644 --- a/Documentation/hwmon/max31790.rst +++ b/Documentation/hwmon/max31790.rst @@ -38,7 +38,7 @@ Sysfs entries fan[1-12]_input RO fan tachometer speed in RPM fan[1-12]_fault RO fan experienced fault fan[1-6]_target RW desired fan speed in RPM -pwm[1-6]_enable RW regulator mode, 0=disabled, 1=manual mode, 2=rpm mode +pwm[1-6]_enable RW regulator mode, 0=disabled (duty cycle=0%), 1=manual mode, 2=rpm mode pwm[1-6] RW read: current pwm duty cycle, write: target pwm duty cycle (0-255) ================== === ======================================================= |