[PATCH 3/5 v2] WATCHDOG: mtx1-wdt: fix GPIO toggling

[PATCH 3/5 v2] WATCHDOG: mtx1-wdt: fix GPIO toggling

[Florian Fainelli]

Commit e391be76 (MIPS: Alchemy: Clean up GPIO registers and accessors)
changed the way the GPIO was toggled. Prior to this patch, we would
always actively drive the GPIO output to either 0 or 1, this patch
drove the GPIO active to 0, and put the GPIO in tristate to drive it
to 1, unfortunately this does not work, revert back to active driving.

Using a signed variable (gstate) to hold the gpio state and using a bit-
wise operation on it also resulted in toggling value from 1 to -2 since
the variable is signed. This value was then passed on to gpio_direction_
output, which always perform a if (value) ... to set the value to the
gpio, so we were always writing a 1 to this GPIO instead of 1 -> 0 -> 1 ...

Signed-off-by: Florian Fainelli <florian@openwrt.org>
---
Changes since v1:
- use gpio_set_value() instead of gpio_direction_output(.., value)

Stable: [2.6.39+]

diff --git a/drivers/watchdog/mtx-1_wdt.c b/drivers/watchdog/mtx-1_wdt.c
index 9b63642..0e51dca 100644
--- a/drivers/watchdog/mtx-1_wdt.c
+++ b/drivers/watchdog/mtx-1_wdt.c
@@ -66,7 +66,7 @@ static struct {
 	int default_ticks;
 	unsigned long inuse;
 	unsigned gpio;
-	int gstate;
+	unsigned int gstate;
 } mtx1_wdt_device;
 
 static void mtx1_wdt_trigger(unsigned long unused)
@@ -78,11 +78,8 @@ static void mtx1_wdt_trigger(unsigned long unused)
 		ticks--;
 
 	/* toggle wdt gpio */
-	mtx1_wdt_device.gstate = ~mtx1_wdt_device.gstate;
-	if (mtx1_wdt_device.gstate)
-		gpio_direction_output(mtx1_wdt_device.gpio, 1);
-	else
-		gpio_direction_input(mtx1_wdt_device.gpio);
+	mtx1_wdt_device.gstate = !mtx1_wdt_device.gstate;
+	gpio_set_value(mtx1_wdt_device.gpio, mtx1_wdt_device.gstate);
 
 	if (mtx1_wdt_device.queue && ticks)
 		mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
@@ -105,7 +102,7 @@ static void mtx1_wdt_start(void)
 	if (!mtx1_wdt_device.queue) {
 		mtx1_wdt_device.queue = 1;
 		mtx1_wdt_device.gstate = 1;
-		gpio_direction_output(mtx1_wdt_device.gpio, 1);
+		gpio_set_value(mtx1_wdt_device.gpio, 1);
 		mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
 	}
 	mtx1_wdt_device.running++;
@@ -120,7 +117,7 @@ static int mtx1_wdt_stop(void)
 	if (mtx1_wdt_device.queue) {
 		mtx1_wdt_device.queue = 0;
 		mtx1_wdt_device.gstate = 0;
-		gpio_direction_output(mtx1_wdt_device.gpio, 0);
+		gpio_set_value(mtx1_wdt_device.gpio, 0);
 	}
 	ticks = mtx1_wdt_device.default_ticks;
 	spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
-- 
1.7.4.1

Re: [stable] [PATCH 3/5 v2] WATCHDOG: mtx1-wdt: fix GPIO toggling

[Greg KH]

On Sun, Jun 12, 2011 at 06:56:28PM +0200, Florian Fainelli wrote:
> Commit e391be76 (MIPS: Alchemy: Clean up GPIO registers and accessors)
> changed the way the GPIO was toggled. Prior to this patch, we would
> always actively drive the GPIO output to either 0 or 1, this patch
> drove the GPIO active to 0, and put the GPIO in tristate to drive it
> to 1, unfortunately this does not work, revert back to active driving.
> 
> Using a signed variable (gstate) to hold the gpio state and using a bit-
> wise operation on it also resulted in toggling value from 1 to -2 since
> the variable is signed. This value was then passed on to gpio_direction_
> output, which always perform a if (value) ... to set the value to the
> gpio, so we were always writing a 1 to this GPIO instead of 1 -> 0 -> 1 ...
> 
> Signed-off-by: Florian Fainelli <florian@openwrt.org>
> ---
> Changes since v1:
> - use gpio_set_value() instead of gpio_direction_output(.., value)
> 
> Stable: [2.6.39+]
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

</formletter>