[PATCH v2 2/2] mfd: da9063: fix watchdog ping execution

[Marco Felsch <m.felsch@pengutronix.de>]

The watchdog resets the system if the watchdog gets pinged to fast.
Between each watchdog ping must be a pause of at least 200ms. This
commit fixes that by rejecting two fast requests.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
Hi,

after the a discussion we decided to change the busy wait behaviour. Now
the driver won't wait and reject the ping-request immediately to ensure
the cool down phase.

Regards,
  Marco

 drivers/mfd/da9063.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/mfd/da9063.c b/drivers/mfd/da9063.c
index 4d459c7f18..b1e4116906 100644
--- a/drivers/mfd/da9063.c
+++ b/drivers/mfd/da9063.c
@@ -14,6 +14,7 @@
  */
 
 #include <common.h>
+#include <clock.h>
 #include <driver.h>
 #include <gpio.h>
 #include <restart.h>
@@ -33,6 +34,7 @@ struct da9063 {
 	struct i2c_client	*client1;
 	struct device_d		*dev;
 	unsigned int		timeout;
+	uint64_t		last_ping;
 };
 
 /* forbidden/impossible value; timeout will be set to this value initially to
@@ -237,6 +239,14 @@ static int da9063_watchdog_ping(struct da9063 *priv)
 	int ret;
 	u8 val;
 
+	/*
+	 * The watchdog has a cool down phase of 200ms and if we ping to fast
+	 * the da9062/3 resets the system. Reject those requests has a maximum
+	 * failure of 10% if the watchdog timeout is set to 2.048s.
+	 */
+	if ((int64_t)(priv->last_ping + 200 * MSECOND - get_time_ns()) > 0)
+		return 0;
+
 	dev_dbg(priv->dev, "ping\n");
 
 	/* reset watchdog timer; register is self clearing */
@@ -245,6 +255,8 @@ static int da9063_watchdog_ping(struct da9063 *priv)
 	if (ret < 0)
 		return ret;
 
+	priv->last_ping = get_time_ns();
+
 	return 0;
 }
 
-- 
2.20.1


_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox