linux-kernel - Re: [PATCH v2 3/4] leds: add LM3533 LED driver

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Date:	Thu, 3 May 2012 11:43:44 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Johan Hovold <jhovold@...il.com>
Cc:	Rob Landley <rob@...dley.net>, Richard Purdie <rpurdie@...ys.net>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Jonathan Cameron <jic23@....ac.uk>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Florian Tobias Schandinat <FlorianSchandinat@....de>,
	Arnd Bergmann <arnd@...db.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-iio@...r.kernel.org, devel@...verdev.osuosl.org,
	linux-fbdev@...r.kernel.org
Subject: Re: [PATCH v2 3/4] leds: add LM3533 LED driver

On Thu, May 03, 2012 at 12:26:38PM +0200, Johan Hovold wrote:

> +What:		/sys/class/leds/<led>/risetime
> +Date:		April 2012
> +KernelVersion:	3.5
> +Contact:	Johan Hovold <jhovold@...il.com>
> +Description:
> +		Set the pattern generator fall and rise times (0..7), where
> +
> +		0 - 2048 us
> +		1 - 262 ms
> +		2 - 524 ms
> +		3 - 1.049 s
> +		4 - 2.097 s
> +		5 - 4.194 s
> +		6 - 8.389 s
> +		7 - 16.78 s
> +

Shouldn't these be controlled by led_blink_set() rather than a custom
ABI?

> +What:		/sys/class/leds/<led>/id
> +Date:		April 2012
> +KernelVersion:	3.5
> +Contact:	Johan Hovold <jhovold@...il.com>
> +Description:
> +		Get the id of this led (0..3).
> +

This should just be a generic LED subsystem thing?

> +What:		/sys/class/leds/<led>/max_current
> +Date:		April 2012
> +KernelVersion:	3.5
> +Contact:	Johan Hovold <jhovold@...il.com>
> +Description:
> +		Set the full-scale current I_{LED_FULLSCALE} (0..31), where
> +
> +		I_{LED_FULLSCALE} = 5mA + max_current * 0.8mA
> +

Shouldn't this be set by platform data, the maximum current you can push
through the LEDs seems like a board dependant thing which won't change
dynamically at runtime.  The brightness can already be varied.

It'd also be nicer if the kernel did the calculation for the user.

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