Messages in this thread | | | Date | Wed, 29 Jun 2011 21:47:22 +0200 | From | Matthias Kaehlcke <> | Subject | Re: [PATCH 1/2] PWM: add pwm framework support |
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El Wed, Jun 29, 2011 at 11:03:34AM +0200 Sascha Hauer ha dit:
> This patch adds framework support for PWM (pulse width modulation) devices. > > The is a barebone PWM API already in the kernel under include/linux/pwm.h, > but it does not allow for multiple drivers as each of them implements the > pwm_*() functions. > > There are other PWM framework patches around from Bill Gatliff. Unlike > his framework this one does not change the existing API for PWMs so that > this framework can act as a drop in replacement for the existing API. > > Why another framework? > > Several people argue that there should not be another framework for PWMs > but they should be integrated into one of the existing frameworks like led > or hwmon. Unlike these frameworks the PWM framework is agnostic to the > purpose of the PWM. In fact, a PWM can drive a LED, but this makes the > LED framework a user of a PWM, like already done in leds-pwm.c. The gpio > framework also is not suitable for PWMs. Every gpio could be turned into > a PWM using timer based toggling, but on the other hand not every PWM hardware > device can be turned into a gpio due to the lack of hardware capabilities. > > This patch does not try to improve the PWM API yet, this could be done in > subsequent patches. > > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Matthias Kaehlcke <matthias@kaehlcke.net>
-- Matthias Kaehlcke Embedded Linux Developer Amsterdam
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