Re: device-tree vs gpio-leds gpio_blink_set

["jonsmirl@xxxxxxxxx" <jonsmirl@xxxxxxxxx>]

On Tue, Apr 24, 2012 at 8:39 AM, jonsmirl@xxxxxxxxx <jonsmirl@xxxxxxxxx> wrote:
> On Tue, Apr 24, 2012 at 8:24 AM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
>> On Mon, Apr 23, 2012 at 7:49 PM, Mark Brown
>> <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx> 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.
>
> I have a board here with a NXP PCA9532 on i2c.
> http://www.nxp.com/documents/data_sheet/PCA9532.pdf
> drivers/leds/leds-pca9532.c
>
> Pins can be:
> GPIO
> hardware blinking LED
> PWM for backlight

The board is using all three of these modes simultaneously.
It is an eval board for the NXP LPC3131.

>
> It might even be an interrupt source, but I haven't dug into it that deep.
>
>>>
>>> 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
>>
>> _______________________________________________
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>> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
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>
>
>
> --
> Jon Smirl
> jonsmirl@xxxxxxxxx



-- 
Jon Smirl
jonsmirl@xxxxxxxxx

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