[PATCH 2/2] ARM: mx5/mx53_evk: Remove unneeded gpio_set_value call

Wed Mar 16 04:33:26 EDT 2011

[added some people to Cc:]

Hello Julia,

On Tue, Mar 15, 2011 at 11:19:53AM +0100, Julia Lawall wrote:
> On Tue, 15 Mar 2011, Uwe Kleine-König wrote:
> 
> > On Tue, Mar 15, 2011 at 10:41:37AM +0100, Julia Lawall wrote:
> > > I tried the following
> > > 
> > > @@
> > > expression E1,E2;
> > > @@
> > > 
> > >       gpio_direction_output(E1,E2);
> > >       ...
> > > -     gpio_set_value(E1,E2);
> > > 
> > > and found occurrences in 15 files.  In some cases there seems to be some 
> > > delay before the call to gpio_set_value.  Does that have any impacton 
> > > whether it is needed?
> > gpio_direction_output(E1,E2) implies gpio_set_value(E1,E2), so unless
> > there is a gpio_set_value(E1,!E2) before gpio_set_value(E1,E2) is a
> > noop.
> > 
> > I still don't know how to work with coccinelle, so if you point me to a
> > concrete location I can be more specific.
> 
> OK.  I have changed the semantic patch to the following:
> 
> @@
> expression E1,E2,E3;
> @@
> 
>       gpio_direction_output(E1,E2);
>       ... when != gpio_set_value(E1,E3)
> -     gpio_set_value(E1,E2);
> 
> Now it doesn't do all the cases where there is an earlier set ofr some 
> other value.  The patch I obtain is below.  This only concerns 5 files.  
> I haven't checked the result at all.
Thanks. So here comes the check.

> diff -u -p a/arch/arm/mach-mx5/board-mx51_babbage.c b/arch/arm/mach-mx5/board-mx51_babbage.c
> --- a/arch/arm/mach-mx5/board-mx51_babbage.c 2011-02-19 08:28:51.000000000 +0100
> +++ b/arch/arm/mach-mx5/board-mx51_babbage.c 2011-03-15 11:17:03.000000000 +0100
> @@ -218,7 +218,6 @@ static inline void babbage_usbhub_reset(
>  
>  	/* USB HUB RESET - De-assert USB HUB RESET_N */
>  	msleep(1);
> -	gpio_set_value(BABBAGE_USB_HUB_RESET, 0);
>  	msleep(1);
>  	gpio_set_value(BABBAGE_USB_HUB_RESET, 1);
>  }
This function is a bit confusing:

	/* Bring USB hub out of reset */
	ret = gpio_request(BABBAGE_USB_HUB_RESET, "GPIO1_7");
	if (ret) {
		...
		return;
	}
	gpio_direction_output(BABBAGE_USB_HUB_RESET, 0);
	/* USB HUB RESET - De-assert USB HUB RESET_N */
	msleep(1);
	gpio_set_value(BABBAGE_USB_HUB_RESET, 0);
	msleep(1);
	gpio_set_value(BABBAGE_USB_HUB_RESET, 1);

IMHO the comments are misleading.  I'd suggest:

	ret = gpio_request_one(BABBAGE_USB_HUB_RESET,
			GPIOF_DIR_OUT | GPIOF_INIT_LOW, "USB hub reset#");
	if (ret) {
		pr_err("failed to request gpio for USB hub reset#: %d\n", ret);
		return;
	}
	msleep(2);
	gpio_set_value(BABBAGE_USB_HUB_RESET, 1);

Fabio?

> @@ -234,7 +233,6 @@ static inline void babbage_fec_reset(voi
>  		return;
>  	}
>  	gpio_direction_output(BABBAGE_FEC_PHY_RESET, 0);
> -	gpio_set_value(BABBAGE_FEC_PHY_RESET, 0);
>  	msleep(1);
>  	gpio_set_value(BABBAGE_FEC_PHY_RESET, 1);
>  }
should use
	gpio_request_one(BABBAGE_FEC_PHY_RESET,
		GPIOF_DIR_OUT | GPIOF_INIT_LOW, "fec-phy-reset");

> diff -u -p a/arch/arm/mach-mx5/board-mx53_evk.c b/arch/arm/mach-mx5/board-mx53_evk.c
> --- a/arch/arm/mach-mx5/board-mx53_evk.c 2011-03-14 17:19:13.000000000 +0100
> +++ b/arch/arm/mach-mx5/board-mx53_evk.c 2011-03-15 11:17:03.000000000 +0100
> @@ -88,7 +88,6 @@ static inline void mx53_evk_fec_reset(vo
>  		return;
>  	}
>  	gpio_direction_output(SMD_FEC_PHY_RST, 0);
> -	gpio_set_value(SMD_FEC_PHY_RST, 0);
>  	msleep(1);
>  	gpio_set_value(SMD_FEC_PHY_RST, 1);
>  }
ditto

> diff -u -p a/arch/arm/mach-omap2/board-omap3evm.c b/arch/arm/mach-omap2/board-omap3evm.c
> --- a/arch/arm/mach-omap2/board-omap3evm.c 2011-03-14 17:19:13.000000000 +0100
> +++ b/arch/arm/mach-omap2/board-omap3evm.c 2011-03-15 11:17:04.000000000 +0100
> @@ -860,7 +860,6 @@ static void __init omap3_evm_init(void)
>  		omap_mux_init_gpio(61, OMAP_PIN_INPUT_PULLUP);
>  		gpio_request(OMAP3_EVM_EHCI_SELECT, "select EHCI port");
>  		gpio_direction_output(OMAP3_EVM_EHCI_SELECT, 0);
> -		gpio_set_value(OMAP3_EVM_EHCI_SELECT, 0);
>  
>  		/* setup EHCI phy reset config */
>  		omap_mux_init_gpio(21, OMAP_PIN_INPUT_PULLUP);
ditto

> diff -u -p a/arch/arm/mach-omap2/board-omap4panda.c b/arch/arm/mach-omap2/board-omap4panda.c
> --- a/arch/arm/mach-omap2/board-omap4panda.c 2011-03-14 17:19:13.000000000 +0100
> +++ b/arch/arm/mach-omap2/board-omap4panda.c 2011-03-15 11:17:04.000000000 +0100
> @@ -129,7 +129,6 @@ static void __init omap4_ehci_init(void)
>  	}
>  	gpio_export(GPIO_HUB_POWER, 0);
>  	gpio_direction_output(GPIO_HUB_POWER, 0);
> -	gpio_set_value(GPIO_HUB_POWER, 0);
Should use gpio_request_one, too. And IMHO gpio_export should only be
called after the direction is set (which is an obsolete comment when
gpio_request_one is used).

>  	/* reset phy+hub */
>  	ret = gpio_request(GPIO_HUB_NRESET, "hub_nreset");
> @@ -139,7 +138,6 @@ static void __init omap4_ehci_init(void)
>  	}
>  	gpio_export(GPIO_HUB_NRESET, 0);
>  	gpio_direction_output(GPIO_HUB_NRESET, 0);
> -	gpio_set_value(GPIO_HUB_NRESET, 0);
>  	gpio_set_value(GPIO_HUB_NRESET, 1);
>  
>  	usbhs_init(&usbhs_bdata);
ditto

> diff -u -p a/arch/arm/mach-pxa/am300epd.c b/arch/arm/mach-pxa/am300epd.c
> --- a/arch/arm/mach-pxa/am300epd.c 2010-03-18 09:06:45.000000000 +0100
> +++ b/arch/arm/mach-pxa/am300epd.c 2011-03-15 11:17:04.000000000 +0100
> @@ -150,8 +150,6 @@ static int am300_init_gpio_regs(struct b
>  		gpio_direction_output(i, 0);
>  
>  	/* go into command mode */
> -	gpio_set_value(CFG_GPIO_PIN, 1);
> -	gpio_set_value(RST_GPIO_PIN, 0);
>  	msleep(10);
>  	gpio_set_value(RST_GPIO_PIN, 1);
>  	msleep(10);
This can probably make use of gpio_request_array.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |