linux-kernel - Re: [PATCH 2/2] leds: Add driver for NCP5623 3-channel I2C LED driver

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Date:	Mon, 27 Jun 2016 07:46:49 +0200
From:	Florian Vaussard <florian.vaussard@...g-vd.ch>
To:	Pavel Machek <pavel@....cz>,
	Jacek Anaszewski <j.anaszewski@...sung.com>
CC:	Florian Vaussard <florian.vaussard@...il.com>,
	<devicetree@...r.kernel.org>, Richard Purdie <rpurdie@...ys.net>,
	Rob Herring <robh+dt@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	<linux-leds@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Vaussard Florian <florian.vaussard@...g-vd.ch>
Subject: Re: [PATCH 2/2] leds: Add driver for NCP5623 3-channel I2C LED driver

Hi Pavel,

Le 26. 06. 16 à 23:49, Pavel Machek a écrit :
> Hi!
> 
>>> +struct ncp5623_led {
>>> +	bool active;
>>> +	unsigned int led_no;
>>> +	struct led_classdev ldev;
>>> +	struct work_struct work;
>>> +	struct ncp5623_priv *priv;
>>> +};
>>> +
>>> +struct ncp5623_priv {
>>> +	struct ncp5623_led leds[NCP5623_MAX_LEDS];
>>
>> Please allocate memory dynamically, depending on the number
>> of LEDs defined in a Device Tree.
> 
> MAX_LEDs is three. Are you sure overhead of dynamic allocation is
> worth it?
> 
> And if this is for RGB leds... very probably device will want to use
> all 3 channels.
> 

I was about to raise the same question during the v2 of this patch. In addition
to your arguments, this also changes the way this array is indexed.

Currently the LED number is used as index, but with dynamic allocation I have to
use an abstract index. This makes some logic a bit harder, especially to check
if the same LED is declared twice in the device tree (duplicated 'reg' property).

Best,
Florian