linux-kernel - Re: [PATCH v5 1/2] leds: tps6105x: add driver for mfd chip led mode

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Date:   Mon, 9 Dec 2019 10:15:02 -0500
From:   Sven Van Asbroeck <thesven73@...il.com>
To:     Dan Murphy <dmurphy@...com>
Cc:     Lee Jones <lee.jones@...aro.org>, Pavel Machek <pavel@....cz>,
        Linus Walleij <linus.walleij@...aro.org>,
        Grigoryev Denis <grigoryev@...twel.ru>,
        Axel Lin <axel.lin@...ics.com>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-leds@...r.kernel.org
Subject: Re: [PATCH v5 1/2] leds: tps6105x: add driver for mfd chip led mode

Thank you for the review, Dan. Some remarks below.

On Mon, Dec 9, 2019 at 9:12 AM Dan Murphy <dmurphy@...com> wrote:
>
> > +     priv->fwnode = device_get_next_child_node(pdev->dev.parent, NULL);
>
> Probably need to check for NULL on the return
>

The driver will work without crashes or oopses even when this returns NULL:
- struct led_init_data . fwnode is optional (can be NULL)
- fwnode_handle_put() ignores NULL arguments

By not checking for NULL here, non-devicetree users can still select
led mode through platform data on the parent mfd driver, and things
will "just work".

Could I persuade you to keep this behaviour?
Perhaps I should put a comment in to clarify?

> > +     ret = regmap_update_bits(tps6105x->regmap, TPS6105X_REG_0,
> > +             TPS6105X_REG0_MODE_MASK | TPS6105X_REG0_TORCHC_MASK,
> > +             TPS6105X_REG0_MODE_TORCH << TPS6105X_REG0_MODE_SHIFT);
> Checkpatch should have warned about alignment here

I used 5.4's checkpatch.pl, but somehow it doesn't warn :(
Will fix that up.