Clarify why we need to ping the watchdog before changing the timeout by
quoting the MAX77714 datasheet.

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>

---

Changes in v5:
 - improve comment to remove misleading ambiguous interpretation
   (Guenter Roeck)

This patch is new in v4. It adds a clarification comment to the max77620
driver taken from v3 patch 7.
---
 drivers/watchdog/max77620_wdt.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/watchdog/max77620_wdt.c b/drivers/watchdog/max77620_wdt.c
index 85ade3c16476..97c12c6167e3 100644
--- a/drivers/watchdog/max77620_wdt.c
+++ b/drivers/watchdog/max77620_wdt.c

@@ -123,6 +123,11 @@ static int max77620_wdt_set_timeout(struct watchdog_device *wdt_dev,
 		break;
 	}
 
+	/*
+	 * "If the value of TWD needs to be changed, clear the system
+	 * watchdog timer first [...], then change the value of TWD."
+	 * (MAX77714 datasheet but applies to MAX77620 too)
+	 */
 	ret = regmap_update_bits(wdt->rmap, wdt->drv_data->reg_cnfg_glbl3,
 				 wdt->drv_data->wdtc_mask, 0x1);
 	if (ret < 0)

-- 
2.25.1