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

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Message-ID: <YEDcYN70TIPlPXv7@workstation.tuxnet>
Date:   Thu, 4 Mar 2021 14:10:56 +0100
From:   Clemens Gruber <clemens.gruber@...ruber.com>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     Sven Van Asbroeck <thesven73@...il.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

Hi Uwe,

On Mon, Mar 01, 2021 at 10:41:15PM +0100, Uwe Kleine-König wrote:
> 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.

I see. Then I'd suggest that we postpone adding these checks until we
get a response from Thierry and if he agrees with you, we could add
these checks in a separate patch series?

Thanks,
Clemens