Re: [PATCH] pwm: add support for Intel Low Power Subsystem PWM

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Tue, Jan 21, 2014 at 08:43:39PM +0100, Thierry Reding wrote:
> The idea behind this is that only a single user can have access to a
> given PWM device at a time. The PWM device's PWMF_REQUESTED flag is set
> (and cleared) under the pwm_lock and any subsequent users will not be
> able to use that specific device (pwm_request() return -EBUSY).
> 
> There is obviously an assumption here that each user knows what they are
> doing and aren't calling any of the public pwm_*() functions
> concurrently. I haven't come across a situation where this is actually a
> problem because typically these functions are called either via sysfs or
> some other higher-level where synchronization is already properly
> handled.
> 
> So the only thing that drivers should be taking care of is synchronizing
> access to registers common to multiple PWM devices.

OK, and since LPSS PWM don't share registers we shouldn't need to do
anything here.

> Does that clarify things?

It does for me, thanks for the explanation.