[U-Boot] [PATCH] mxs_gpio: fix the handling in gpio_direction_output()

[U-Boot] [PATCH] mxs_gpio: fix the handling in gpio_direction_output()

[Michael Heimpold]

Setting the direction and an output value should be done by
1) set the desired output value,
2) switch to output.

If this is done in the inverse order, there can be a glitch on
the GPIO line.

This patch fixes this by using the order as described above.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>
---
 drivers/gpio/mxs_gpio.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/mxs_gpio.c b/drivers/gpio/mxs_gpio.c
index d9a7a3a..da0199b 100644
--- a/drivers/gpio/mxs_gpio.c
+++ b/drivers/gpio/mxs_gpio.c
@@ -95,10 +95,10 @@ int gpio_direction_output(unsigned gpio, int value)
 	struct mxs_register_32 *reg =
 		(struct mxs_register_32 *)(MXS_PINCTRL_BASE + offset);
 
-	writel(1 << PAD_PIN(gpio), &reg->reg_set);
-
 	gpio_set_value(gpio, value);
 
+	writel(1 << PAD_PIN(gpio), &reg->reg_set);
+
 	return 0;
 }
 
-- 
1.7.10.4

[U-Boot] [PATCH] mxs_gpio: fix the handling in gpio_direction_output()

[Stefano Babic]

Hi Michael,

On 03/11/2013 22:59, Michael Heimpold wrote:
> Setting the direction and an output value should be done by
> 1) set the desired output value,
> 2) switch to output.
> 
> If this is done in the inverse order, there can be a glitch on
> the GPIO line.
> 
> This patch fixes this by using the order as described above.
> 
> Signed-off-by: Michael Heimpold <mhei@heimpold.de>
> ---
>  drivers/gpio/mxs_gpio.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpio/mxs_gpio.c b/drivers/gpio/mxs_gpio.c
> index d9a7a3a..da0199b 100644
> --- a/drivers/gpio/mxs_gpio.c
> +++ b/drivers/gpio/mxs_gpio.c
> @@ -95,10 +95,10 @@ int gpio_direction_output(unsigned gpio, int value)
>  	struct mxs_register_32 *reg =
>  		(struct mxs_register_32 *)(MXS_PINCTRL_BASE + offset);
>  
> -	writel(1 << PAD_PIN(gpio), &reg->reg_set);
> -
>  	gpio_set_value(gpio, value);
>  
> +	writel(1 << PAD_PIN(gpio), &reg->reg_set);
> +

Yes, we had the same fix for mxc (commit
04c79cbd5f8f773aa7823feec6e77862e7e6426f)

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] mxs_gpio: fix the handling in gpio_direction_output()

[Stefano Babic]

On 03/11/2013 22:59, Michael Heimpold wrote:
> Setting the direction and an output value should be done by
> 1) set the desired output value,
> 2) switch to output.
> 
> If this is done in the inverse order, there can be a glitch on
> the GPIO line.
> 
> This patch fixes this by using the order as described above.
> 
> Signed-off-by: Michael Heimpold <mhei@heimpold.de>
> ---

Applied to u-boot-imx, thanks.

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
=====================================================================