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

To: Wim Van Sebroeck <>,,, Manuel Lauss <>
Subject: [PATCH 3/3] WATCHDOG: mtx1-wdt: fix GPIO toggling
From: Florian Fainelli <>
Date: Thu, 2 Jun 2011 14:54:21 +0200
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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 <>
diff --git a/drivers/watchdog/mtx-1_wdt.c b/drivers/watchdog/mtx-1_wdt.c
index 16086f8..9756da9 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)
        /* 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_direction_output(mtx1_wdt_device.gpio, mtx1_wdt_device.gstate);
        if (mtx1_wdt_device.queue && ticks)
                mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);

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