Our product is an embedded Linux system, a charging station controller with the possibility to attach a fan. This fan can be controlled via PWM and the Linux driver we use for it is "pwmfan". On top in userspace, we use fancontrol and pwmconfig from lm-sensors. We recently switched over to a newer Linux kernel version and noticed that commit b99152d4f04b379e31db6c1a2dda6b272c92039b (hwmon: (pwm-fan) Switch regulator dynamically) introduced an issue: now the pwm1_enable file is present in the sysfs API but the way the driver implements this is not compatible with the expectations by fancontrol/pwmconfig: According to https://www.kernel.org/doc/Documentation/hwmon/sysfs-interface: -snip- pwm[1-*]_enable Fan speed control method: 0: no fan speed control (i.e. fan at full speed) 1: manual fan speed control enabled (using pwm[1-*]) 2+: automatic fan speed control enabled Check individual chip documentation files for automatic mode details. -snap- This is also what pwmconfig and fancontrol expects. But the driver implementation does this: Quote from https://www.kernel.org/doc/Documentation/hwmon/pwm-fan.rst -snip- 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 -snap- So we have a regression here when using fancontrol/pwmconfig with newer kernels. As workaround, we have adapted the two mentioned scripts. The uses approach is to check whether this special hwmon driver is used and ignore the pwm1_enable file in this moment. We are not sure, what the "correct" resolution here would be. So just take this a discussion proposal. Signed-off-by: Michael Heimpold <michael.heimpold@xxxxxxxxxxxxxx> --- PS: I'm not subscribed to the list, please keep Cc-ing me, thanks. prog/pwm/fancontrol | 11 ++++++++--- prog/pwm/pwmconfig | 21 ++++++++++++++++++--- 2 files changed, 26 insertions(+), 6 deletions(-) diff --git a/prog/pwm/fancontrol b/prog/pwm/fancontrol index 886a7367..5158be1a 100755 --- a/prog/pwm/fancontrol +++ b/prog/pwm/fancontrol @@ -399,9 +399,12 @@ declare -A PWM_ORIG_STATE function pwmdisable() { local ENABLE=${1}_enable + local NAME="$(dirname ${1})/name" + local DRVNAME="$(cat $NAME)" - # No enable file? Just set to max - if [ ! -f $ENABLE ] + # No enable file? Just set to max; + # pwmfan driver implements enable file, but with different purpose + if [ ! -f $ENABLE ] || [ "$DRVNAME" = "pwmfan" ] then echo $MAX > $1 return 0 @@ -470,8 +473,10 @@ function pwmdisable() function pwmenable() { local ENABLE=${1}_enable + local NAME="$(dirname ${1})/name" + local DRVNAME="$(cat $NAME)" - if [ -f $ENABLE ] + if [ -f $ENABLE ] && [ "$DRVNAME" != "pwmfan" ] then # save the original pwmN_control state, e.g. 1 for manual or 2 for auto, # and the value from pwmN diff --git a/prog/pwm/pwmconfig b/prog/pwm/pwmconfig index edcbde9e..3e4af78a 100755 --- a/prog/pwm/pwmconfig +++ b/prog/pwm/pwmconfig @@ -157,6 +157,14 @@ function print_devices() function is_pwm_auto() { local ENABLE=${1}_enable + local NAME="$(dirname ${1})/name" + local DRVNAME="$(cat $NAME)" + + # pwmfan driver does not implement auto mode + if [ "$DRVNAME" = "pwmfan" ] + then + return 1 + fi if [ -f $ENABLE ] then @@ -173,9 +181,12 @@ function is_pwm_auto() function pwmdisable() { local ENABLE=${1}_enable + local NAME="$(dirname ${1})/name" + local DRVNAME="$(cat $NAME)" - # No enable file? Just set to max - if [ ! -f $ENABLE ] + # No enable file? Just set to max; + # pwmfan driver implements enable file, but with different purpose + if [ ! -f $ENABLE ] || [ "$DRVNAME" = "pwmfan" ] then echo $MAX > $1 return 0 @@ -213,8 +224,12 @@ function pwmdisable() function pwmenable() { local ENABLE=${1}_enable + local NAME="$(dirname ${1})/name" + local DRVNAME="$(cat $NAME)" - if [ -w $ENABLE ] + # enable pwm, but only if driver is not pwmfan since + # this one implements enable with different purpose + if [ -w $ENABLE ] && [ "$DRVNAME" != "pwmfan" ] then echo 1 2>/dev/null > $ENABLE if [ $? -ne 0 ] -- 2.34.1
