From b633b9c8fe26519f3abaee3724115fec7b86aab2 Mon Sep 17 00:00:00 2001
From: Lukasz Majewski <lukma@denx.de>
Date: Sun, 19 Feb 2017 23:24:38 +0100
Subject: ti: wdt: omap: Disable watchdog timer before performing
 initialization

The OMAP WDT IP block requires to be stopped before any write to its
registers is performed.

This problem has been thoroughly described in Linux kernel:

"watchdog: omap: assert the counter being stopped before reprogramming:
SHA1: 530c11d432727c697629ad5f9d00ee8e2864d453

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>

diff --git a/drivers/watchdog/omap_wdt.c b/drivers/watchdog/omap_wdt.c
index 7ea4b60..7b1f429 100644
--- a/drivers/watchdog/omap_wdt.c
+++ b/drivers/watchdog/omap_wdt.c
@@ -81,10 +81,32 @@ static int omap_wdt_set_timeout(unsigned int timeout)
 	return 0;
 }
 
+void hw_watchdog_disable(void)
+{
+	struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
+
+	/*
+	 * Disable watchdog
+	 */
+	writel(0xAAAA, &wdt->wdtwspr);
+	while (readl(&wdt->wdtwwps) != 0x0)
+		;
+	writel(0x5555, &wdt->wdtwspr);
+	while (readl(&wdt->wdtwwps) != 0x0)
+		;
+}
+
 void hw_watchdog_init(void)
 {
 	struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
 
+	/*
+	 * Make sure the watchdog is disabled. This is unfortunately required
+	 * because writing to various registers with the watchdog running has no
+	 * effect.
+	 */
+	hw_watchdog_disable();
+
 	/* initialize prescaler */
 	while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WCLR)
 		;
@@ -104,18 +126,3 @@ void hw_watchdog_init(void)
 	while ((readl(&wdt->wdtwwps)) & WDT_WWPS_PEND_WSPR)
 		;
 }
-
-void hw_watchdog_disable(void)
-{
-	struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
-
-	/*
-	 * Disable watchdog
-	 */
-	writel(0xAAAA, &wdt->wdtwspr);
-	while (readl(&wdt->wdtwwps) != 0x0)
-		;
-	writel(0x5555, &wdt->wdtwspr);
-	while (readl(&wdt->wdtwwps) != 0x0)
-		;
-}
-- 
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