On Tuesday 15 February 2022 20:11:07 Armin Wolf wrote: > Right now, the only way to test if setting manual/auto fan control works > is to edit and recompile the module, which may be too cumbersome for > the average user. There is also another way suitable for testing purposes which do not requires any kernel patch. Call iopl(3) syscall which changes I/O privilege level to 3 and which allows to poke I/O registers. > Allow for specifying the desired fan mode control method when loading > the module, but taint the kernel if so since there is the possibility > for strange side effects on non-whitelisted models. > Also update docs and kernel-parameters.txt accordingly. > > Tested on a Dell Inspiron 3505. > > Signed-off-by: Armin Wolf <W_Armin@xxxxxx> > --- > .../admin-guide/kernel-parameters.txt | 3 +++ > Documentation/hwmon/dell-smm-hwmon.rst | 21 ++++++++++------ > drivers/hwmon/dell-smm-hwmon.c | 25 +++++++++++++------ > 3 files changed, 35 insertions(+), 14 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index d68053db21cc..4f1b6c2b7ed1 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -968,6 +968,9 @@ > dell_smm_hwmon.fan_max= > [HW] Maximum configurable fan speed. > > + dell_smm_hwmon.fan_mode_method= > + [HW] Method to use for changing fan mode. > + > dfltcc= [HW,S390] > Format: { on | off | def_only | inf_only | always } > on: s390 zlib hardware support for compression on > diff --git a/Documentation/hwmon/dell-smm-hwmon.rst b/Documentation/hwmon/dell-smm-hwmon.rst > index beec88491171..564d99cda869 100644 > --- a/Documentation/hwmon/dell-smm-hwmon.rst > +++ b/Documentation/hwmon/dell-smm-hwmon.rst > @@ -67,13 +67,16 @@ for your hardware. It is possible that codes that work for other > laptops actually work for yours as well, or that you have to discover > new codes. > > -Check the list ``i8k_whitelist_fan_control`` in file > -``drivers/hwmon/dell-smm-hwmon.c`` in the kernel tree: as a first > -attempt you can try to add your machine and use an already-known code > -pair. If, after recompiling the kernel, you see that ``pwm1_enable`` > -is present and works (i.e., you can manually control the fan speed), > -then please submit your finding as a kernel patch, so that other users > -can benefit from it. Please see > +As a first step, you can load the module with the module parameter > +``fan_mode_method`` set to 1 to test if your hardware works with > +an already know method for disabling automatic BIOS fan control. > +If ``pwm1_enable`` is now present and works (i.e., you can > +manually control the fan speed), then please submit your finding > +as a kernel patch, so that other users can benefit from it. > +Just add your model to the list ``i8k_whitelist_fan_control`` in > +file ``drivers/hwmon/dell-smm-hwmon.c`` in the kernel tree and use > +the already known code pair. > +Please read > :ref:`Documentation/process/submitting-patches.rst <submittingpatches>` > for information on submitting patches. > > @@ -120,6 +123,10 @@ Module parameters > Maximum configurable fan speed. (default: > autodetect) > > +* fan_mode_method:uint > + Method to use for changing fan mode (default: > + from whitelist) > + > Legacy ``/proc`` interface > -------------------------- > > diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c > index 9949eeb79378..1c4cc516c8b2 100644 > --- a/drivers/hwmon/dell-smm-hwmon.c > +++ b/drivers/hwmon/dell-smm-hwmon.c > @@ -111,6 +111,10 @@ static uint fan_max; > module_param(fan_max, uint, 0); > MODULE_PARM_DESC(fan_max, "Maximum configurable fan speed (default: autodetect)"); > > +static uint fan_mode_method; > +module_param_unsafe(fan_mode_method, uint, 0); > +MODULE_PARM_DESC(fan_mode_method, "Method to use for changing fan mode (default: from whitelist)"); No, please really do not introduce another kernel parameter for this driver. There are already many and we do not need to extend this list. > + > struct smm_regs { > unsigned int eax; > unsigned int ebx; > @@ -677,7 +681,7 @@ static umode_t dell_smm_is_visible(const void *drvdata, enum hwmon_sensor_types > > break; > case hwmon_pwm_enable: > - if (data->auto_fan) > + if (data->auto_fan && data->manual_fan) > /* > * There is no command for retrieve the current status > * from BIOS, and userspace/firmware itself can change > @@ -1282,14 +1286,21 @@ static int __init dell_smm_probe(struct platform_device *pdev) > data->i8k_fan_max = fan_max ? : I8K_FAN_HIGH; /* Must not be 0 */ > data->i8k_pwm_mult = DIV_ROUND_UP(255, data->i8k_fan_max); > > - fan_control = dmi_first_match(i8k_whitelist_fan_control); > - if (fan_control && fan_control->driver_data) { > - const struct i8k_fan_control_data *control = fan_control->driver_data; > + /* value specified via module param overrides whitelist */ > + if (fan_mode_method > 0 && fan_mode_method <= ARRAY_SIZE(i8k_fan_control_data)) { > + data->manual_fan = i8k_fan_control_data[fan_mode_method - 1].manual_fan; > + data->auto_fan = i8k_fan_control_data[fan_mode_method - 1].auto_fan; > + } else { > + fan_control = dmi_first_match(i8k_whitelist_fan_control); > + if (fan_control && fan_control->driver_data) { > + const struct i8k_fan_control_data *control = fan_control->driver_data; > > - data->manual_fan = control->manual_fan; > - data->auto_fan = control->auto_fan; > - dev_info(&pdev->dev, "enabling support for setting automatic/manual fan control\n"); > + data->manual_fan = control->manual_fan; > + data->auto_fan = control->auto_fan; > + } > } > + if (data->manual_fan && data->auto_fan) > + dev_info(&pdev->dev, "enabling support for setting automatic/manual fan control\n"); > > if (!fan_mult) { > /* > -- > 2.30.2 >