device-tree vs gpio-leds gpio_blink_set

[Linus Walleij]

On Mon, Apr 23, 2012 at 7:49 PM, Mark Brown
<broonie at opensource.wolfsonmicro.com> wrote:
> On Mon, Apr 23, 2012 at 11:22:43AM +0000, Arnd Bergmann wrote:
>> On Monday 23 April 2012, Arnaud Patard wrote:
>
>> > Does anyone know how to solve that ?
>
>> One way to solve it would be to add a blink function to gpiolib so
>> that the gpio-led driver can access it through a common wrapper
>> and we can make the orion_gpio_set_blink() function a pointer in
>> the gpio_chip structure rather than an export from
>> arch/arm/plat-orion/gpio.c. I've put a few people on Cc that might
>> have an opion on this.
>
> Another idea would be to use pinctrl and represent the blink as a
> special function.  Not sure that's sensible though.

I would rather say that anything automatically toggling
a GPIO pin on/off at specified intervals is HW-controlled
GPIO PWM.

So this would be something that gets to be modeled in the
PWM subsystem, but there is no such thing (I know Sascha et
al was working on that at one point.)

But in my dreams it would be in
drivers/pwm/pwm-gpio.c and then anything that needs
an auto-toggling GPIO pin could use that PWM interface.
And only then it would be given hooks into the gpio driver,
like with some #ifdef in the .h file for gpiolib that expose
this hook only to the PWM subsystem.

But I guess I won't have it my way :-)

Currently, drivers/leds/leds-gpio.c has a
platform-specific callback to set blink period. How do we
replace that with something that can call generic code on
a larger scale?

Maybe it should go into gpiolib then, but I'm not sure at
all.

BTW: can leds-pwm.c use leds-gpio.c and exploit the blink
callback there? (I hope so...)

Yours,
Linus Walleij