Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200924192455.2484005-1-j.neuschaefer@gmx.net>
 <20200924192455.2484005-4-j.neuschaefer@gmx.net> <CAHp75VdUHPsuvDPLnfP9sM2p1FDiCsjkCf1SSM-y02ZsQxSDWQ@mail.gmail.com>
 <20200925213207.GA2510@latitude>
In-Reply-To: <20200925213207.GA2510@latitude>
From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Tue, 29 Sep 2020 19:37:21 +0300
Message-ID: <CAHp75VchfQ-djkK6u+fLjq6kfqpzb0nqSLJOe76cb5S3J_F9GQ@mail.gmail.com>
Subject: Re: [PATCH v3 3/7] mfd: Add base driver for Netronix embedded controller
To:     =?UTF-8?Q?Jonathan_Neusch=C3=A4fer?= <j.neuschaefer@gmx.net>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Lee Jones <lee.jones@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Alessandro Zummo <a.zummo@towertech.it>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Heiko Stuebner <heiko.stuebner@theobroma-systems.com>,
        Stephan Gerhold <stephan@gerhold.net>,
        Lubomir Rintel <lkundrak@v3.sk>,
        Mark Brown <broonie@kernel.org>, allen <allen.chen@ite.com.tw>,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        devicetree <devicetree@vger.kernel.org>,
        linux-pwm@vger.kernel.org,
        "open list:REAL TIME CLOCK (RTC) SUBSYSTEM" 
        <linux-rtc@vger.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
        Heiko Stuebner <heiko@sntech.de>,
        Josua Mayer <josua.mayer@jm0.eu>,
        Andreas Kemnade <andreas@kemnade.info>,
        Arnd Bergmann <arnd@arndb.de>, Daniel Palmer <daniel@0x0f.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Sat, Sep 26, 2020 at 12:32 AM Jonathan Neusch=C3=A4fer
<j.neuschaefer@gmx.net> wrote:
> On Fri, Sep 25, 2020 at 12:29:45PM +0300, Andy Shevchenko wrote:
> > On Thu, Sep 24, 2020 at 10:26 PM Jonathan Neusch=C3=A4fer
> > <j.neuschaefer@gmx.net> wrote:

...

> > > +               dev_alert(&poweroff_restart_client->dev,
> > > +                         "Failed to power off (err =3D %d)\n", res);
> >
> > alert? This needs to be explained.
>
> I copied the dev_alert from drivers/mfd/rn5t618.c.
>
> Upon reconsideration, I'm not sure what the correct log level would be,
> but _warn seems enough, or maybe _err is better

It's up to you to decide, but crit/alert and similar has to be
justified (commit message / comment in the code).

...

> > > +       /*
> > > +        * NOTE: The lower half of the reset value is not sent, becau=
se sending
> > > +        * it causes an error
> >
> > Why? Any root cause? Perhaps you need to send 0xffff ?
>
> Unknown, because I don't have the EC firmware for analysis. The vendor
> kernel sends 0xff00 and gets an error.
>
> Sending 0xffff doesn't help.

Maybe a slightly elaborated comment that it's copied from the vendor
kernel (which is?).

> > > +        */

...

> > > +       dev_info(ec->dev,
> > > +                "Netronix embedded controller version %04x detected.=
\n",
> > > +                version);
> >
> > This info level may confuse users if followed by an error path.
>
> Right. I suppose printing incompatible versions is still useful, so how
> about something like the following?
>
>
>        /* Bail out if we encounter an unknown firmware version */
>        switch (version) {
>        case 0xd726: /* found in Kobo Aura */
>                dev_info(ec->dev,
>                         "Netronix embedded controller version %04x detect=
ed.\n",
>                         version);
>                break;
>        default:
>                dev_err(ec->dev,
>                         "Netronix embedded controller version %04x is not=
 supported.\n",
>                         version);
>                return -ENODEV;
>        }

This is better.

...

> > > +               WARN_ON(poweroff_restart_client);
> >
> > WARN_ON? All these alerts, WARNs, BUGs must be explained. Screaming to
> > the user is not good if it wasn't justified.
>
> poweroff_restart_client being already set is not a situation that should
> happen (and would indicate a bug in this driver, AFAICT), but I guess
> the log message could be better in that case...

As per above.

--=20
With Best Regards,
Andy Shevchenko