linux-kernel - Re: [PATCH v3] leds: Add MAX6956 driver

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Date:	Mon, 21 May 2012 23:30:28 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
Cc:	Bryan Wu <bryan.wu@...onical.com>,
	Richard Purdie <rpurdie@...ys.net>, kernel@...gutronix.de,
	linux-kernel@...r.kernel.org,
	Grant Likely <grant.likely@...retlab.ca>,
	Linus Walleij <linus.walleij@...ricsson.com>
Subject: Re: [PATCH v3] leds: Add MAX6956 driver

On Mon, May 21, 2012 at 9:33 PM, Uwe Kleine-König
<u.kleine-koenig@...gutronix.de> wrote:

> +config LEDS_MAX6956
> +       tristate "LED support for MAX6956 LED Display Driver and I/O Expander"
> +       depends on LEDS_CLASS
> +       depends on GPIOLIB

Shouldn't this be select GPIOLIB?

You seem to require it when using this driver.

Better than hiding it if not selecting GPIOLIB somewhere else?

> +struct max6956_ddata {
> +       struct device *dev;
> +
> +       struct mutex lock;
> +
> +       struct regmap *regmap;
> +
> +       struct gpio_chip gpio_chip;
> +
> +       struct max6956_pdata pdata;
> +
> +       struct max6956_led_ddata leds[32];
> +
> +       const char *gpio_names[32];
> +};

You can never have enough whitespace? ;-)

Anyway, so this thing has a gpio_chip and leds.

The archaic way is to create mfd/max-6956.c and have this
MFD device spawn two cells, one for GPIO landing in
driver/gpio/gpio-max6956.c and one for LED landing in
leds/leds-max6956.c, then mediate register read/writes and
regmap in the MFD driver.

The MFD driver decide using platform data whether each
line should be used for a LED or GPIO.

Is there some problem with this design pattern?

Yours,
Linus Walleij
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