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gpio: spear_gpio: Fix gpio_set_value() implementation

PATCH New Axel Lin 2 participants 2 messages Sep 16, 2013 – Jul 4, 2014 GPIO

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Axel Lin

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#0 lore raw

PATCH v2 1/1 gpio: spear_gpio: Fix gpio_set_value() implementation

In current gpio_set_value() implementation, it always sets the gpio control bit no matter the value argument is 0 or 1. Thus the GPIOs never set to low. This patch fixes this bug.

The address bus is used as a mask on read/write operations, so that independent software drivers can set their GPIO bits without affecting any other pins in a single write operation. Thus we don't need a read-modify-write to update the register.

Signed-off-by Axel Lin <[email protected]>
Acked-by Stefan Roese <[email protected]>
Reviewed-by Vipin Kumar <[email protected]>
Reviewed-by Michael Trimarchi <[email protected]>

---
v2: Update commit log to explain why a read-modify-write is not necessary
for clearing specific GPIO bit.
Also added Michael Trimarchi's reviewed-by tag since he does review the patch and said the patch is fine.

 drivers/gpio/spear_gpio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
drivers/gpio/spear_gpio.c +4 -1
index 367b670..6fb4117 100644
@@ -36,7 +36,10 @@ int gpio_set_value(unsigned gpio, int value)
 {
 	struct gpio_regs *regs = (struct gpio_regs *)CONFIG_GPIO_BASE;
 
-	writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+	if (value)
+		writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+	else
+		writel(0, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
 
 	return 0;
 }
Signature · 1 line
1.8.1.2
#1 lore raw

PATCH v2 1/1 gpio: spear_gpio: Fix gpio_set_value() implementation

Hi Axel,

Quoted 28 lines · Axel Lin

In current gpio_set_value() implementation, it always sets the gpio control bit no matter the value argument is 0 or 1. Thus the GPIOs never set to low. This patch fixes this bug.

The address bus is used as a mask on read/write operations, so that independent software drivers can set their GPIO bits without affecting any other pins in a single write operation. Thus we don't need a read-modify-write to update the register.

Signed-off-by Axel Lin <[email protected]>
Acked-by Stefan Roese <[email protected]>
Reviewed-by Vipin Kumar <[email protected]>
Reviewed-by Michael Trimarchi <[email protected]>

---
v2: Update commit log to explain why a read-modify-write is not necessary
for clearing specific GPIO bit.
Also added Michael Trimarchi's reviewed-by tag since he does review the patch and said the patch is fine.

 drivers/gpio/spear_gpio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
drivers/gpio/spear_gpio.c +0 -0
index 367b670..6fb4117 100644
@@ -36,7 +36,10 @@ int gpio_set_value(unsigned gpio, int value)
 {

drivers/gpio/spear_gpio.c int gpio_set_value(unsigned gpio, int value) · line 45

Quoted 10 lines
drivers/gpio/spear_gpio.c +4 -1
 	struct gpio_regs *regs = (struct gpio_regs *)CONFIG_GPIO_BASE;
 
-	writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+	if (value)
+		writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+	else
+		writel(0, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
 
 	return 0;
 }

Applied to u-boot-arm/master, thanks!

Amicalement,

Signature · 1 line
Albert.