linux-kernel - [PATCH] Watchdog: Fix for settimeout issue

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Date:	Mon, 30 Apr 2012 12:10:31 +0530
From:	Ashish Jangam <ashish.jangam@...tcummins.com>
To:	Wim Van Sebroeck <wim@...ana.be>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
	Anthony Olech <Anthony.Olech@...semi.com>,
	<sameo@...ux.intel.com>
Subject: [PATCH] Watchdog: Fix for settimeout issue

Some devices have a fixed minimum elapse time and a ping before this
elapse time causes error condition. This patch fix this issue in the
settimeout operation.
---
 drivers/watchdog/watchdog_dev.c |    7 ++++++-
 include/linux/watchdog.h        |    3 +++
 2 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 8558da9..fb6076c 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -41,6 +41,7 @@
 #include <linux/miscdevice.h>	/* For handling misc devices */
 #include <linux/init.h>		/* For __init/__exit/... */
 #include <linux/uaccess.h>	/* For copy_to_user/put_user/... */
+#include <linux/delay.h>	/* For delay (like mdelay) */
 
 /* make sure we only register one /dev/watchdog device */
 static unsigned long watchdog_dev_busy;
@@ -228,7 +229,11 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
 			return err;
 		/* If the watchdog is active then we send a keepalive ping
 		 * to make sure that the watchdog keep's running (and if
-		 * possible that it takes the new timeout) */
+		 * possible that it takes the new timeout) Also we care
+		 * for watchdog which needs min elapse time before a ping.
+		 */
+		if (wdd->min_elapse_time)
+			mdelay(wdd->min_elapse_time);
 		watchdog_ping(wdd);
 		/* Fall */
 	case WDIOC_GETTIMEOUT:
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index ac40716..37d25b8 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -95,6 +95,8 @@ struct watchdog_ops {
  * @timeout:	The watchdog devices timeout value.
  * @min_timeout:The watchdog devices minimum timeout value.
  * @max_timeout:The watchdog devices maximum timeout value.
+ * @min_elapse_time: The watchdog devices minimum elapse time before
+ *		the ping.
  * @driver-data:Pointer to the drivers private data.
  * @status:	Field that contains the devices internal status bits.
  *
@@ -111,6 +113,7 @@ struct watchdog_device {
 	unsigned int timeout;
 	unsigned int min_timeout;
 	unsigned int max_timeout;
+	unsigned int min_elapse_time;
 	void *driver_data;
 	unsigned long status;
 /* Bit numbers for status flags */


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