linux-kernel - Re: [PATCH v5 1/7] pwm: pca9685: Switch to atomic API

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Message-ID: <20210301214115.xolncig676tgnxwn@pengutronix.de>
Date:   Mon, 1 Mar 2021 22:41:15 +0100
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Sven Van Asbroeck <thesven73@...il.com>
Cc:     Clemens Gruber <clemens.gruber@...ruber.com>,
        linux-pwm@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        David Jander <david@...tonic.nl>
Subject: Re: [PATCH v5 1/7] pwm: pca9685: Switch to atomic API

On Thu, Dec 17, 2020 at 12:10:10PM -0500, Sven Van Asbroeck wrote:
> On Thu, Dec 17, 2020 at 11:48 AM Clemens Gruber
> <clemens.gruber@...ruber.com> wrote:
> >
> > I can initialize the values to 0 of course and check the file for other
> > places with missing initializations.
> >
> > Or would it be better to check the return codes of regmap_read/write in
> > such cases? I'm not sure.
> 
> I think that checking the regmap_read/write return values is overkill
> in this driver. These functions can't realistically fail, except if the i2c
> bus is bad, i.e. h/w failure or intermittency. And that's an externality
> which I believe we can ignore.
> 
> Maybe Thierry or Uwe have further insights here.

I'm a fan of full checking, but I'm not sure what's Thierry's position
on that.

My reasoning is: If the bus is bad and a request to modify the PWM fails
because of that, the PWM consumer probably wants to know.

Best regards
Uwe

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

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