[PATCH 3.10 031/173] gpio: twl4030: Fix regression for twl gpio output

Greg Kroah-Hartman
2013-12-02T21:16:26Z

From: Tony Lindgren <tony@atomide.com>

commit 0b2aa8bed3e13892fcac77e4f50ec6e80125469d upstream.

Commit c111feabe2e2 (gpio: twl4030: Cache the direction and output
states in private data) improved things in general, but caused a
regression for setting the GPIO output direction.

The change reorganized twl_direction_out() and twl_set() and swapped
the function names around in the process. While doing that, a bug got
introduced that's not obvious while reading the patch as it appears
as no change to the code.

The bug is we now call function twl4030_set_gpio_dataout() twice in
both twl_direction_out() and twl_set(). Instead, we should first
call twl_direction_out() in twl_direction_out() followed by
twl4030_set_gpio_dataout() in twl_set().

This regression probably has gone unnoticed for a long time as the
bootloader may have set the GPIO direction properly in many cases.
This fixes at least the LCD panel not turning on omap3 LDP for
example.

Cc: linux-gpio@vger.kernel.org
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpio/gpio-twl4030.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/gpio/gpio-twl4030.c
+++ b/drivers/gpio/gpio-twl4030.c
@@ -354,17 +354,18 @@ static void twl_set(struct gpio_chip *ch
static int twl_direction_out(struct gpio_chip *chip, unsigned offset, int value)
{
struct gpio_twl4030_priv *priv = to_gpio_twl4030(chip);
+ int ret = -EINVAL;

mutex_lock(&priv->mutex);
if (offset < TWL4030_GPIO_MAX)
- twl4030_set_gpio_dataout(offset, value);
+ ret = twl4030_set_gpio_direction(offset, 0);

priv->direction |= BIT(offset);
mutex_unlock(&priv->mutex);

twl_set(chip, offset, value);

- return 0;
+ return ret;
}

static int twl_to_irq(struct gpio_chip *chip, unsigned offset)