[RFC PATCH 06/15] pwm: define a new pwm_state struct

Thierry Reding thierry.reding at gmail.com
Mon Jul 20 03:09:26 PDT 2015


On Mon, Jul 20, 2015 at 12:01:16PM +0200, Boris Brezillon wrote:
> On Mon, 20 Jul 2015 10:04:59 +0200
> Thierry Reding <thierry.reding at gmail.com> wrote:
> 
> > On Wed, Jul 01, 2015 at 10:21:52AM +0200, Boris Brezillon wrote:
> > [...]
> > > diff --git a/include/linux/pwm.h b/include/linux/pwm.h
> > [...]
> > > +struct pwm_state {
> > > +	unsigned int		period; 	/* in nanoseconds */
> > > +	unsigned int		duty_cycle;	/* in nanoseconds */
> > > +	enum pwm_polarity	polarity;
> > > +};
> > 
> > No need for the extra padding here.
> 
> What do you mean by "extra padding" ?
> I just reused the indentation used in the pwm_device struct.

Yeah, I have a local patch to fix that up. I find it useless to pad
things like this, and it has the downside that it will become totally
inconsistent (or cause a lot of churn by reformatting) if ever you add a
field that extends beyond the padding. Single spaces don't have any such
drawbacks and, in my opinion, look just as good.

> Would you prefer something like that ?
> 
> struct pwm_state {
> 	unsigned int period; 		/* in nanoseconds */
> 	unsigned int duty_cycle;	/* in nanoseconds */
> 	enum pwm_polarity polarity;
> };

Yeah. I'd say even the comments would be more suited in a kerneldoc-
style comment:

	/**
	 * struct pwm_state - state of a PWM channel
	 * @period: PWM period (in nanoseconds)
	 * @duty_cycle: PWM duty cycle (in nanoseconds)
	 * @polarity: PWM polarity
	 */
	struct pwm_state {
		unsigned int period;
		unsigned int duty_cycle;
		enum pwm_polarity polarity;
	};

This is something that users will need to deal with, so eventually
somebody might look at this via some DocBook generated HTML or PDF.

Thierry
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