linux-kernel - Re: [PATCH] pwm: Rename pwm_get_state() to better reflect its semantic

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Message-ID: <20210406134356.dda74heeshkwdarw@pengutronix.de>
Date:   Tue, 6 Apr 2021 15:43:56 +0200
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Heiko Stuebner <heiko@...ech.de>, linux-doc@...r.kernel.org,
        David Airlie <airlied@...ux.ie>,
        Michael Turquette <mturquette@...libre.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Liam Girdwood <lgirdwood@...il.com>,
        Fabio Estevam <festevam@...il.com>, linux-clk@...r.kernel.org,
        Alexandre Torgue <alexandre.torgue@...com>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jonathan Corbet <corbet@....net>,
        Lee Jones <lee.jones@...aro.org>, Chen-Yu Tsai <wens@...e.org>,
        linux-stm32@...md-mailman.stormreply.com,
        linux-rockchip@...ts.infradead.org,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        NXP Linux Team <linux-imx@....com>,
        linux-input@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
        linux-pwm@...r.kernel.org, Daniel Vetter <daniel@...ll.ch>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Mark Brown <broonie@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Fabrice Gasnier <fabrice.gasnier@...com>,
        linux-arm-kernel@...ts.infradead.org,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Support Opensource <support.opensource@...semi.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        linux-kernel@...r.kernel.org,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>
Subject: Re: [PATCH] pwm: Rename pwm_get_state() to better reflect its
 semantic

Hello Thierry,

On Tue, Apr 06, 2021 at 01:16:31PM +0200, Thierry Reding wrote:
> On Tue, Apr 06, 2021 at 09:30:36AM +0200, Uwe Kleine-König wrote:
> > Given that lowlevel drivers usually cannot implement exactly what a
> > consumer requests with pwm_apply_state() there is some rounding involved.
> > 
> > pwm_get_state() traditionally returned the setting that was requested most
> > recently by the consumer (opposed to what was actually implemented in
> > hardware in reply to the last request). To make this semantic obvious
> > rename the function.
> > 
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> > ---
> >  Documentation/driver-api/pwm.rst           |  6 +++-
> >  drivers/clk/clk-pwm.c                      |  2 +-
> >  drivers/gpu/drm/i915/display/intel_panel.c |  4 +--
> >  drivers/input/misc/da7280.c                |  2 +-
> >  drivers/input/misc/pwm-beeper.c            |  2 +-
> >  drivers/input/misc/pwm-vibra.c             |  4 +--
> >  drivers/pwm/core.c                         |  4 +--
> >  drivers/pwm/pwm-atmel-hlcdc.c              |  2 +-
> >  drivers/pwm/pwm-atmel.c                    |  2 +-
> >  drivers/pwm/pwm-imx27.c                    |  2 +-
> >  drivers/pwm/pwm-rockchip.c                 |  2 +-
> >  drivers/pwm/pwm-stm32-lp.c                 |  4 +--
> >  drivers/pwm/pwm-sun4i.c                    |  2 +-
> >  drivers/pwm/sysfs.c                        | 18 ++++++------
> >  drivers/regulator/pwm-regulator.c          |  4 +--
> >  drivers/video/backlight/pwm_bl.c           | 10 +++----
> >  include/linux/pwm.h                        | 34 ++++++++++++++--------
> >  17 files changed, 59 insertions(+), 45 deletions(-)
> 
> Honestly, I don't think this is worth the churn. If you think people
> will easily get confused by this then a better solution might be to more
> explicitly document the pwm_get_state() function to say exactly what it
> returns.

I'm not so optimistic that people become aware of the semantic just
because there is documentation describing it and I strongly believe that
a good name for functions is more important than accurate documentation.

If you don't agree, what do you think about the updated wording in
Documentation/driver-api/pwm.rst?

> But there's no need to make life difficult for everyone by
> renaming this to something as cumbersome as this.

I don't expect any merge conflicts (and if still a problem occurs
resolving should be trivial enough). So I obviously don't agree to your
weighing.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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