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

Dirk Behme dirk.behme at de.bosch.com
Mon Jul 15 15:58:27 CEST 2013


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 at 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



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