Re: [PATCH 2/2] pwm: Add GPIO PWM driver

[Olliver Schinagl <oliver@schinagl.nl>]

Hey Vincent,

On 15-09-2020 16:02, Vincent Whitchurch wrote:
> On Thu, Sep 03, 2020 at 11:15:31AM +0200, Olliver Schinagl wrote:
>> On 14-08-2020 17:55, Vincent Whitchurch wrote:
>>> Add a software PWM which toggles a GPIO from a high-resolution timer.
>>>
>>> This will naturally not be as accurate or as efficient as a hardware
>>> PWM, but it is useful in some cases.  I have for example used it for
>>> evaluating LED brightness handling (via leds-pwm) on a board where the
>>> LED was just hooked up to a GPIO, and for a simple verification of the
>>> timer frequency on another platform.
>>>
>>> Since high-resolution timers are used, sleeping gpio chips are not
>>> supported and are rejected in the probe function.
>>>
>>> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
>>> ---
>>> While preparing this driver for posting, I found a pwm-gpio driver posted to
>>> the lists way back in 2015 by Olliver Schinagl:
>>>
>>>    https://lore.kernel.org/linux-pwm/1445895161-2317-8-git-send-email-o.schinagl@ultimaker.com/
>>>
>> Thanks for reminding me there :) As I think I still use this driver, I
>> don't mind migrating to this one (if merged) but how do you suggests to
>> proceed with regards to multiple PWM's, as this is how I am using it
>> currently. E.g. how do we merge them? I'm fine with 'taking the simpler
>> code method' for a start point, but i guess I solved that part
>> (somewhat) in 2015 :p
> 
> Since this is just a software construct, the simplest way would just be
> to create multiple instances in the device tree if you want multiple
> PWMs, wouldn't it?
> 
Not entirely, as they are no longer 'logically grouped'?

Olliver