[U-Boot] [PATCH] mxc_gpio: Correct the GPIO handling in gpio_direction_output()

[U-Boot] [PATCH] mxc_gpio: Correct the GPIO handling in gpio_direction_output()

[Dirk Behme]

Setting the direction and an output value should be done by

First, set the desired output value.

Then, switch to output.

If this is done in the inverse order, like at the moment,
there can be a glitch on the GPIO line while switching first
the old output value and aftwards the new one.

Fix this by inverting the order of the direction/set_value
calls.

Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
---
 drivers/gpio/mxc_gpio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/mxc_gpio.c b/drivers/gpio/mxc_gpio.c
index a388064..1d820d4 100644
--- a/drivers/gpio/mxc_gpio.c
+++ b/drivers/gpio/mxc_gpio.c
@@ -143,10 +143,10 @@ int gpio_direction_input(unsigned gpio)
 
 int gpio_direction_output(unsigned gpio, int value)
 {
-	int ret = mxc_gpio_direction(gpio, MXC_GPIO_DIRECTION_OUT);
+	int ret = gpio_set_value(gpio, value);
 
 	if (ret < 0)
 		return ret;
 
-	return gpio_set_value(gpio, value);
+	return mxc_gpio_direction(gpio, MXC_GPIO_DIRECTION_OUT);
 }
-- 
1.8.2

[U-Boot] [PATCH] mxc_gpio: Correct the GPIO handling in gpio_direction_output()

[Stefano Babic]

On 15/07/2013 15:58, Dirk Behme wrote:
> Setting the direction and an output value should be done by
> 
> First, set the desired output value.
> 
> Then, switch to output.
> 
> If this is done in the inverse order, like at the moment,
> there can be a glitch on the GPIO line while switching first
> the old output value and aftwards the new one.
> 
> Fix this by inverting the order of the direction/set_value
> calls.

Right, thanks to fix this !

> 
> Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
> ---
>  drivers/gpio/mxc_gpio.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpio/mxc_gpio.c b/drivers/gpio/mxc_gpio.c
> index a388064..1d820d4 100644
> --- a/drivers/gpio/mxc_gpio.c
> +++ b/drivers/gpio/mxc_gpio.c
> @@ -143,10 +143,10 @@ int gpio_direction_input(unsigned gpio)
>  
>  int gpio_direction_output(unsigned gpio, int value)
>  {
> -	int ret = mxc_gpio_direction(gpio, MXC_GPIO_DIRECTION_OUT);
> +	int ret = gpio_set_value(gpio, value);
>  
>  	if (ret < 0)
>  		return ret;
>  
> -	return gpio_set_value(gpio, value);
> +	return mxc_gpio_direction(gpio, MXC_GPIO_DIRECTION_OUT);
>  }
> 

Acked-by: Stefano Babic <sbabic@denx.de>

Best regards,
Stefano Babic

-- 
=====================================================================
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de
=====================================================================

[U-Boot] [PATCH] mxc_gpio: Correct the GPIO handling in gpio_direction_output()

[Stefano Babic]

On 15/07/2013 15:58, Dirk Behme wrote:
> Setting the direction and an output value should be done by
> 
> First, set the desired output value.
> 
> Then, switch to output.
> 
> If this is done in the inverse order, like at the moment,
> there can be a glitch on the GPIO line while switching first
> the old output value and aftwards the new one.
> 
> Fix this by inverting the order of the direction/set_value
> calls.
> 
> Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
> ---

Applied to u-boot-imx, thanks !

Best regards,
SWtefano Babic


-- 
=====================================================================
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de
=====================================================================