Re: [PATCH v3 3/7] mfd: Add base driver for Netronix embedded controller

[Andy Shevchenko]

On Sat, Sep 26, 2020 at 12:32 AM Jonathan Neuschäfer
<j.neuschaefer@xxxxxxx> wrote:
> On Fri, Sep 25, 2020 at 12:29:45PM +0300, Andy Shevchenko wrote:
> > On Thu, Sep 24, 2020 at 10:26 PM Jonathan Neuschäfer
> > <j.neuschaefer@xxxxxxx> wrote:

...

> > > +               dev_alert(&poweroff_restart_client->dev,
> > > +                         "Failed to power off (err = %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, because 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 detected.\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.

-- 
With Best Regards,
Andy Shevchenko