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 axel.lin@ingics.com Acked-by: Stefan Roese sr@denx.de Reviewed-by: Vipin Kumar vipin.kumar@st.com Reviewed-by: Michael Trimarchi michael@amarulasolutions.com --- 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(-)
diff --git a/drivers/gpio/spear_gpio.c b/drivers/gpio/spear_gpio.c index 367b670..6fb4117 100644 --- a/drivers/gpio/spear_gpio.c +++ b/drivers/gpio/spear_gpio.c @@ -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, ®s->gpiodata[DATA_REG_ADDR(gpio)]); + if (value) + writel(1 << gpio, ®s->gpiodata[DATA_REG_ADDR(gpio)]); + else + writel(0, ®s->gpiodata[DATA_REG_ADDR(gpio)]);
return 0; }