Re: [RESEND PATCH v3 4/4] leds: Add a multicolor LED driver to group monochromatic LEDs

[Jean-Jacques Hiblot]

On 17/09/2022 10:37, Andy Shevchenko wrote:
> On Sat, Sep 17, 2022 at 11:14 AM Jean-Jacques Hiblot
> <jjhiblot@xxxxxxxxxxxxxxx> wrote:
> > By allowing to group multiple monochrome LED into multicolor LEDs,
> > all involved LEDs can be controlled in-sync. This enables using effects
> > using triggers, etc.
> ...
>
> > +config LEDS_GRP_MULTICOLOR
> > +       tristate "Multi-color LED grouping support"
> > +       help
> > +         This option enables support for monochrome LEDs that are
> > +         grouped into multicolor LEDs.
> What will be the module name in case of "m" choice?
>
> ...
>
> > +       struct led_mcg_priv *priv =
> > +               container_of(mc_cdev, struct led_mcg_priv, mc_cdev);
> One line?
>
> ...
>
> > +               /*
> > +                * Scale the intensity according the max brightness of the
> > +                * monochromatic LED
> Usually we put a grammar period at the end of sentences in multi-line comments.
>
> > +                */
> ...
>
> > +               actual_led_brightness = DIV_ROUND_CLOSEST(
> > +                       mono->max_brightness * mc_cdev->subled_info[i].brightness,
> > +                       mc_cdev->led_cdev.max_brightness);
> Can you fix an indentation, so it won't leave the line ending by open
> parenthesis? I believe with the help of a temporary variable it can be
> easily achieved.
Could be done but I have no good name for the variable and I think it 
would just make things harder to understand. In that form I think it is 
clear that this is a cross-multiplication.
> ...
>
> > +       for (;;) {
> > +               struct led_classdev *led_cdev;
> > +               led_cdev = devm_of_led_get(dev, count);
> Why _of_ variant? Please, make this OF independent since it's
> pretending to cover not only OF-based systems.

This is not OF independent. It could be, but that will wait until 
someone needs it. I don't know much about ACPI and have no hardware to 
test it on.

I'll add the missing  dependency on OF in the Kconfig.

> > +               if (IS_ERR(led_cdev)) {
> > +                       /* Reached the end of the list ? */
> > +                       if (PTR_ERR(led_cdev) == -ENOENT)
> > +                               break;
> Looks like the above needs an _optional() variant
>
> > +                       return dev_err_probe(dev, PTR_ERR(led_cdev),
> > +                                            "Unable to get led #%d", count);
> > +               }
> ...
>
> > +               priv->monochromatics = devm_krealloc(dev, priv->monochromatics,
> > +                                       count * sizeof(*priv->monochromatics),
> > +                                       GFP_KERNEL);
> This needs at minimum to use one of the helpers from overflow.h,
> ideally you may implement devm_krealloc_array() as a suitable wrapper
> for that.
>
> > +               if (!priv->monochromatics)
> > +                       return -ENOMEM;
> ...
>
> > +       subled = devm_kzalloc(dev, count * sizeof(*subled), GFP_KERNEL);
> NIH devm_kcalloc()
>
> > +       if (!subled)
> > +               return -ENOMEM;
> --
> With Best Regards,
> Andy Shevchenko