[PATCH] watchdog: rti_wdt: Set min_hw_heartbeat_ms to accommodate 5% safety margin

Judith Mendez
2024-04-03T21:24:39Z

On AM62x, the watchdog is pet before the valid window
is open. Fix min_hw_heartbeat and accommodate a 5% safety
margin with the exception of open window size < 10%,
which shall use <5% due to the smaller open window size.

Signed-off-by: Judith Mendez <jm@ti.com>
---
drivers/watchdog/rti_wdt.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
index 8e1be7ba0103..0b16ada659cc 100644
--- a/drivers/watchdog/rti_wdt.c
+++ b/drivers/watchdog/rti_wdt.c
@@ -92,7 +92,7 @@ static int rti_wdt_start(struct watchdog_device *wdd)
* to be 50% or less than that; we obviouly want to configure the open
* window as large as possible so we select the 50% option.
*/
- wdd->min_hw_heartbeat_ms = 500 * wdd->timeout;
+ wdd->min_hw_heartbeat_ms = 550 * wdd->timeout;

/* Generate NMI when wdt expires */
writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL);
@@ -126,31 +126,33 @@ static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd, u32 wsize)
* be petted during the open window; not too early or not too late.
* The HW configuration options only allow for the open window size
* to be 50% or less than that.
+ * To avoid any glitches, we accommodate 5% safety margin, with the
+ * exception of open window size < 10%.
*/
switch (wsize) {
case RTIWWDSIZE_50P:
- /* 50% open window => 50% min heartbeat */
- wdd->min_hw_heartbeat_ms = 500 * heartbeat;
+ /* 50% open window => 55% min heartbeat */
+ wdd->min_hw_heartbeat_ms = 550 * heartbeat;
break;

case RTIWWDSIZE_25P:
- /* 25% open window => 75% min heartbeat */
- wdd->min_hw_heartbeat_ms = 750 * heartbeat;
+ /* 25% open window => 80% min heartbeat */
+ wdd->min_hw_heartbeat_ms = 800 * heartbeat;
break;

case RTIWWDSIZE_12P5:
- /* 12.5% open window => 87.5% min heartbeat */
- wdd->min_hw_heartbeat_ms = 875 * heartbeat;
+ /* 12.5% open window => 92.5% min heartbeat */
+ wdd->min_hw_heartbeat_ms = 925 * heartbeat;
break;

case RTIWWDSIZE_6P25:
- /* 6.5% open window => 93.5% min heartbeat */
- wdd->min_hw_heartbeat_ms = 935 * heartbeat;
+ /* 6.5% open window => 96.5% min heartbeat */
+ wdd->min_hw_heartbeat_ms = 965 * heartbeat;
break;

case RTIWWDSIZE_3P125:
- /* 3.125% open window => 96.9% min heartbeat */
- wdd->min_hw_heartbeat_ms = 969 * heartbeat;
+ /* 3.125% open window => 97.9% min heartbeat */
+ wdd->min_hw_heartbeat_ms = 979 * heartbeat;
break;

default:
--
2.43.2