linux-kernel - Re: [RFC PATCH RESEND 2/3] leds: upboard: Add LED support

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Message-ID: <20180425070227.exixjo64spvt36vo@localhost>
Date:   Wed, 25 Apr 2018 08:02:27 +0100
From:   Javier Arteaga <javier@...tex.com>
To:     Pavel Machek <pavel@....cz>
Cc:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Dan O'Donovan <dan@...tex.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Lee Jones <lee.jones@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH RESEND 2/3] leds: upboard: Add LED support

Hi Pavel,

On Wed, Apr 25, 2018 at 08:41:33AM +0200, Pavel Machek wrote:
> On Sat 2018-04-21 09:50:08, Javier Arteaga wrote:
> > Allow userspace to use the on-board LEDs as "upboard:<color>:".
> > 
> > Signed-off-by: Javier Arteaga <javier@...tex.com>
> 
> > +static enum led_brightness upboard_led_brightness_get(struct led_classdev *cdev)
> > +{
> > +	struct upboard_led *led = container_of(cdev, struct upboard_led, cdev);
> > +	int brightness = 0;
> > +
> > +	regmap_field_read(led->field, &brightness);
> > +
> > +	return brightness;
> > +};
> 
> I'm slightly confused here. Is each led controlled by single bit?

Yes. Each regmap field is one bit wide.

> What is going on with ";" at end of function? We don't do that.

Huh, I totally missed this. It's all throughout the patchset too, and
it's going away in v2 of course.

> If it is single bit, max_brightness should be one, and != LED_OFF test
> should not be needed.

Got it. Will do for v2.

Thanks for your time!