Technically this is not required because disabling the PWM should be
enough. However, when support for atomic operations was implemented in
the PWM subsystem, only actual changes to the PWM channel are applied
during pwm_config(), which means that during after resume from suspend
the old settings won't be applied.
One possible solution is for the PWM driver to implement its own PM
operations such that settings from before suspend get applied on resume.
This has the disadvantage of completely ignoring any particular ordering
requirements that PWM user drivers might have, so it is best to leave it
up to the user drivers to apply the settings that they want at the
appropriate time.
Another way to solve this would be to read back the current state of the
PWM at the time of resume. That way, in case the configuration was lost
during suspend, applying the old settings in PWM user drivers would
actually get them applied because they differ from the current settings.
However, not all PWM drivers support reading the hardware state, and not
all hardware may support it.
The best workaround at this point seems to be to let PWM user drivers
tell the PWM subsystem that the PWM is turned off by, in addition to
disabling it, also setting the duty cycle to 0. This causes the resume
operation to apply a configuration that is different from the current
configuration, resulting in the proper state from before suspend getting
restored.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Probe deferrals aren't actual errors, so silence the error message in
case the PWM cannot yet be acquired.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The PWM framework has clarified the concept of reference PWM config (the
platform dependent config retrieved from the DT or the PWM lookup table)
and real PWM state.
Use pwm_get_args() when the PWM user wants to retrieve this reference
config and not the current state.
This is part of the rework allowing the PWM framework to support
hardware readout and expose real PWM state even when the PWM has just
been requested (before the user calls pwm_config/enable/disable()).
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This platform driver has a OF device ID table but the OF module
alias information is not created so module autoloading won't work.
Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
pwm_config() must be called with a duty cycle of 0 prior to calling
pwm_disable() to ensure that the pwm signal is set to low.
Reported-by: Markus Reichl <m.reichl@fivetechno.de>
Tested-by: Markus Reichl <m.reichl@fivetechno.de>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>
Reviewed-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
of_device_id is always used as const.
(See driver.of_match_table and open firmware functions)
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Address the following sparse warnings.
drivers/hwmon/pwm-fan.c:176:5: warning:
symbol 'pwm_fan_of_get_cooling_data' was not declared. Should it be static?
drivers/hwmon/pwm-fan.c:176:5: warning:
no previous prototype for 'pwm_fan_of_get_cooling_data'
pwm_fan_of_get_cooling_data is only used in the pwm-fan driver and thus should
be declared static.
Cc: Lukasz Majewski <l.majewski@samsung.com>
Acked-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The PWM FAN device can now be used as a thermal cooling device.
Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Acked-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This patch provides code for reading PWM FAN configuration data via
device tree. The pwm-fan can work with full speed when configuration
is not provided. However, errors are propagated when wrong DT bindings
are found.
Additionally the struct pwm_fan_ctx has been extended.
Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
It was necessary to decouple code handling writing to sysfs from the one
responsible for setting PWM of the fan.
Due to that, new __set_pwm() method was extracted, which is responsible for
only setting new PWM duty cycle.
Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The state of a PWM output is not clearly defined after resume. Some PWM
drivers do not restore the duty cycle upon resume, thus it is necessary to
manually restore the correct value.
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The dev_set_drvdata() call is equivalent to the platform_set_drvdata() call in
next line.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The pwm-fan driver enables control of fans connected to PWM lines.
This driver uses the PWM framework, so it is compatible with all
PWM devices that provide drivers through the PWM framework.
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Reviewed-by: Varka Bhadram <varkabhadram@gmail.com>
Reviewed-by: Tobias Klauser <tklauser@distanz.ch>
[Guenter Roeck: Last argument to devm_of_pwm_get is pointer, use NULL]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Guenter Roeck