linux-kernel - [PATCH v1] watchdog: imx2_wdt: clear WDOG_HW

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Date:   Tue, 11 May 2021 19:20:32 +0800
From:   Robin Gong <yibin.gong@....com>
To:     wim@...ux-watchdog.org, linux@...ck-us.net, shawnguo@...nel.org,
        s.hauer@...gutronix.de, festevam@...il.com
Cc:     linux-imx@....com, kernel@...gutronix.de,
        linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1] watchdog: imx2_wdt: clear WDOG_HW_RUNNING before suspend

Since watchdog_ping_work is not freezable so that it maybe scheduled before
imx2_wdt_resume where watchdog clock enabled, hence, kernel will hang in
imx2_wdt_ping without clock, and then watchdog reset happen. Prevent the
above case by clearing WDOG_HW_RUNNING before suspend, and restore it with
ping in imx2_wdt_resume.

Signed-off-by: Robin Gong <yibin.gong@....com>
---
 drivers/watchdog/imx2_wdt.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
index b84f80f..d3751e9 100644
--- a/drivers/watchdog/imx2_wdt.c
+++ b/drivers/watchdog/imx2_wdt.c
@@ -357,6 +357,13 @@ static int __maybe_unused imx2_wdt_suspend(struct device *dev)
 		 */
 		__imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 		imx2_wdt_ping(wdog);
+
+		/*
+		 * clear WDOG_HW_RUNNING to prevent watchdog_ping_work running
+		 * before imx2_wdt_resume where clock enabled, otherwise kernel
+		 * will hang and watchdog reset happen then.
+		 */
+		clear_bit(WDOG_HW_RUNNING, &wdog->status);
 	}
 
 	clk_disable_unprepare(wdev->clk);
@@ -386,6 +393,7 @@ static int __maybe_unused imx2_wdt_resume(struct device *dev)
 	if (imx2_wdt_is_running(wdev)) {
 		imx2_wdt_set_timeout(wdog, wdog->timeout);
 		imx2_wdt_ping(wdog);
+		set_bit(WDOG_HW_RUNNING, &wdog->status);
 	}
 
 	return 0;
-- 
2.7.4