From b99152d4f04b379e31db6c1a2dda6b272c92039b Mon Sep 17 00:00:00 2001 From: Alexander Stein <alexander.stein@ew.tq-group.com> Date: Wed, 14 Sep 2022 17:31:37 +0200 Subject: hwmon: (pwm-fan) Switch regulator dynamically This adds the enable attribute which is used to select if zero PWM duty means to switch off regulator and PWM or to keep them enabled but at inactive PWM output level. Depending on the select enable mode, turn off the regulator and PWM if the PWM duty is zero, or keep them enabled. This is especially important for fan using inverted PWM signal polarity. Having regulator supplied and PWM disabled, some PWM controllers provide the active, rather than inactive signal. With this change the shutdown as well as suspend/resume paths require modifcations as well. Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com> Link: https://lore.kernel.org/r/20220914153137.613982-6-alexander.stein@ew.tq-group.com Signed-off-by: Guenter Roeck <linux@roeck-us.net> --- Documentation/hwmon/pwm-fan.rst | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'Documentation/hwmon') diff --git a/Documentation/hwmon/pwm-fan.rst b/Documentation/hwmon/pwm-fan.rst index 82fe96742fee..f77998b204ef 100644 --- a/Documentation/hwmon/pwm-fan.rst +++ b/Documentation/hwmon/pwm-fan.rst @@ -18,3 +18,15 @@ the hwmon's sysfs interface. The fan rotation speed returned via the optional 'fan1_input' is extrapolated from the sampled interrupts from the tachometer signal within 1 second. + +The driver provides the following sensor accesses in sysfs: + +=============== ======= ======================================================= +fan1_input ro fan tachometer speed in RPM +pwm1_enable rw keep enable mode, defines behaviour when pwm1=0 + 0 -> disable pwm and regulator + 1 -> enable pwm; if pwm==0, disable pwm, keep regulator enabled + 2 -> enable pwm; if pwm==0, keep pwm and regulator enabled + 3 -> enable pwm; if pwm==0, disable pwm and regulator +pwm1 rw relative speed (0-255), 255=max. speed. +=============== ======= ======================================================= -- cgit v1.2.3