linux-kernel - Re: [RFC PATCH 1/7] pwm: rename the PWM_POLARITY

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Date:   Thu, 19 Mar 2020 13:10:26 +0100
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Oleksandr Suvorov <oleksandr.suvorov@...adex.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        devicetree@...r.kernel.org, linux-pwm@...r.kernel.org,
        Paul Barker <pbarker@...sulko.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        Igor Opaniuk <igor.opaniuk@...adex.com>,
        Philippe Schenker <philippe.schenker@...adex.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>,
        Fabio Estevam <festevam@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Kevin Hilman <khilman@...libre.com>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Maxime Ripard <mripard@...nel.org>,
        NXP Linux Team <linux-imx@....com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Cercueil <paul@...pouillou.net>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Ray Jui <rjui@...adcom.com>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Scott Branden <sbranden@...adcom.com>,
        Shawn Guo <shawnguo@...nel.org>,
        bcm-kernel-feedback-list@...adcom.com,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-rockchip@...ts.infradead.org
Subject: Re: [RFC PATCH 1/7] pwm: rename the PWM_POLARITY_INVERSED enum

Hello,

[dropping Tony Prisk <linux@...sktech.co.nz> from recipients]

On Thu, Mar 19, 2020 at 01:40:28PM +0200, Oleksandr Suvorov wrote:
> Thierry, I see the PWM core converts the bit field "third cell" into
> the polarity variable.
> Now I probably understand your sight and agree that we shouldn't give
> the same names to bits in bitfield (dts) and values of a variable.
> 
> But there are lots of useless "0" values of third cell of "pwms"
> option in dts files.
> 
> I see 2 ways now:
> - just remove all "0" "third cell" from "pwms" options in dts files. I
> see this "0" confuses some people.

Then you have to overwrite pwm-cells of the provider. If there are two
PWMs used from the same provider and only one is inverted this won't
work. (Not entirely sure I understood your suggestion.) So I don't like
this suggestion.

And also in my eyes this isn't clearer, just more complicated to use.

> - convert pwm_state.polarity into pwm_state.flags and use bitfield
>   directly from dtb.
>   It simplifies the parsing logic and makes adding new flags easier.

*shrug*, I don't care much.

Best regards
Uwe

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