linux-kernel - Re: [PATCH v5 05/46] pwm: introduce the pwm

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Message-ID: <20160412150627.7084665d@bbrezillon>
Date:	Tue, 12 Apr 2016 15:06:27 +0200
From:	Boris Brezillon <boris.brezillon@...e-electrons.com>
To:	Thierry Reding <thierry.reding@...il.com>
Cc:	linux-pwm@...r.kernel.org,
	Mike Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>, linux-clk@...r.kernel.org,
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	Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-input@...r.kernel.org, Bryan Wu <cooloney@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
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	Alexander Shiyan <shc_work@...l.ru>, Milo Kim <milo.kim@...com>
Subject: Re: [PATCH v5 05/46] pwm: introduce the pwm_args concept

On Tue, 12 Apr 2016 13:39:12 +0200
Thierry Reding <thierry.reding@...il.com> wrote:

> On Wed, Mar 30, 2016 at 10:03:28PM +0200, Boris Brezillon wrote:
> > Currently the PWM core mixes the current PWM state with the per-platform
> > reference config (specified through the PWM lookup table, DT definition or
> > directly hardcoded in PWM drivers).
> > 
> > Create a pwm_args struct to store this reference config, so that PWM users
> > can differentiate the current config from the reference one.
> > 
> > Patch all places where pwm->args should be initialized. We keep the
> > pwm_set_polarity/period() calls until all PWM users are patched to
> > use pwm_args instead of pwm_get_period/polarity().
> 
> Perhaps a helper would be useful? Something like:
> 
> 	static inline void
> 	pwm_apply_args(struct pwm_device *pwm, const struct pwm_args *args)
> 	{
> 		pwm_set_duty_cycle(pwm, args->duty_cycle);
> 		pwm_set_period(pwm, args->period);
> 	}
> 
> ? That would make it slightly easier to get rid of it again after all
> clients have been converted.
> 
> With the exception of pwm-clps711x all of these args are set at of_xlate
> time (for DT) or from the lookup table in pwm_get() (for non-DT), so it
> might even be possible to move this call to the core, so that removal of
> it will be a one-liner.

Okay, I think I misunderstood your suggestion. I thought you wanted
this helper to set the reference config, but you actually want to apply
a new state based on the PWM reference values.

Except that pwm_args does not contain all the required information to
apply a full config (args->duty_cycle and args->enable do not exist).

This being said, in my v6 I moved the content of
pwm_regulator_adjust_pwm_config() (patch 27) into a generic helper
(pwm_adjust_config()). This helper is doing pretty much what you're
suggesting here (but again, I'm not sure I correctly understood your
suggestion :-/).

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com