linux-kernel - Re: GPIO support for HTC Dream

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Message-ID: <4B1ECAC2.5090009@bluewatersys.com>
Date:	Wed, 09 Dec 2009 10:53:06 +1300
From:	Ryan Mallon <ryan@...ewatersys.com>
To:	Pavel Machek <pavel@....cz>
CC:	Arve Hj?nnev?g <arve@...roid.com>,
	kernel list <linux-kernel@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	Brian Swetland <swetland@...gle.com>,
	Daniel Walker <dwalker@...eaurora.org>,
	Iliyan Malchev <malchev@...gle.com>
Subject: Re: GPIO support for HTC Dream

Pavel Machek wrote:
> Hi!
> 
>>> +#undef MODULE_PARAM_PREFIX
>>> +#define MODULE_PARAM_PREFIX "board_dream."
>> This looks a bit dodgy. Is this
>> (http://lkml.indiana.edu/hypermail/linux/kernel/0903.0/02768.html) the
>> preferred way?
> 
> I don't think that would help that much here....

Okay, but what is the reason for overriding MODULE_PARAM_PREFIX? Maybe a
comment explaining?

>>> +static void update_pwrsink(unsigned gpio, unsigned on)
>>> +{
>>> +	switch(gpio) {
>>> +	case DREAM_GPIO_UI_LED_EN:
>>> +		break;
>>> +	case DREAM_GPIO_QTKEY_LED_EN:
>>> +		break;
>>> +	}
>>> +}
>> What is this function for?
> 
> Power accounting... should be removed. Fixed.
> 
>>> +static void dream_gpio_irq_ack(unsigned int irq)
>>> +{
>>> +	int bank = DREAM_INT_TO_BANK(irq);
>>> +	uint8_t mask = DREAM_INT_TO_MASK(irq);
>>> +	int reg = DREAM_BANK_TO_STAT_REG(bank);
>>> +	/*printk(KERN_INFO "dream_gpio_irq_ack irq %d\n", irq);*/
>> pr_debug, or just remove it?
> 
> Remove.
> 
>>> +	desc->chip->ack(irq);
>>> +}
>> Some blank lines here and there would make this more readable. All your
>> code is wedged together :-).
> 
> Well, added some blank lines; not sure it is improvement.

This function was just an example, the patch lacked blank lines in
general. Squashed up code is hard to read.

>>> +#define DREAM_INT_TO_BANK(n) ((n - DREAM_INT_START) / DREAM_INT_BANK0_COUNT)
>>> +#define DREAM_INT_TO_MASK(n) (1U << ((n - DREAM_INT_START) & 7))
>>> +#define DREAM_BANK_TO_MASK_REG(bank) \
>>> +	(bank ? DREAM_GPIO_INT_MASK1_REG : DREAM_GPIO_INT_MASK0_REG)
>>> +#define DREAM_BANK_TO_STAT_REG(bank) \
>>> +	(bank ? DREAM_GPIO_INT_STAT1_REG : DREAM_GPIO_INT_STAT0_REG)
>> Are these needed outside of the gpiolib code? If not, they should be
>> moved there. I also think they should have lower case names since they
>> act like a function, and make the code where they are used nicer to
>> read.
> 
> I guess these logically belong here.
> 
> No, macros are macros, that means upcase.

container_of, min, swap, etc are macros too. It is easier to read this
if they are lower case because they are typically used for initialising
variables, ie:

	int bank = dream_int_to_bank(irq);

Is easier (IMHO) to read than:
	
	int bank = DREAM_INT_TO_BANK(irq);


>> Thats big, hard to read, has about 3 blank lines total and no comments.
> 
> I tried to improve it, but it needs more. Here are my cleanups.
> 									Pavel

Looks better overall.

> diff --git a/arch/arm/mach-msm/board-dream.c b/arch/arm/mach-msm/board-dream.c
> index 4758957..3e8e54a 100644
> --- a/arch/arm/mach-msm/board-dream.c
> +++ b/arch/arm/mach-msm/board-dream.c
> @@ -59,6 +59,23 @@ static void __init dream_fixup(struct machine_desc *desc, struct tag *tags,
>  
>  static void __init dream_init(void)
>  {
> +	gpio_set_value(DREAM_GPIO_UI_LED_EN, 1);
> +        mdelay(300);
> +	gpio_set_value(DREAM_GPIO_UI_LED_EN, 0);
> +        mdelay(300);
> +        gpio_set_value(DREAM_GPIO_UI_LED_EN, 1);
> +	mdelay(300);
> +        gpio_set_value(DREAM_GPIO_UI_LED_EN, 0);
> +	mdelay(300);
> +        gpio_set_value(DREAM_GPIO_UI_LED_EN, 1);
> +        mdelay(300);
> +        gpio_set_value(DREAM_GPIO_UI_LED_EN, 0);
> +        mdelay(300);
> +	gpio_set_value(DREAM_GPIO_UI_LED_EN, 1);
> +        mdelay(300);
> +	gpio_set_value(DREAM_GPIO_UI_LED_EN, 0);
> +        mdelay(300);
> +

Indentation looks screwy here. Also, is this meant to blink the leds?
There is a 2.4 second hard delay here, which is horrible.

~Ryan

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