linux-watchdog.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
To: wim@linux-watchdog.org, linux@roeck-us.net, shawnguo@kernel.org
Cc: linux-watchdog@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, grzegorz.jaszczyk@linaro.org,
	Michal Koziel <michal.koziel@emlogic.no>
Subject: [PATCH 2/2] watchdog: imx2_wdg: notify wdog subsystem about wdog suspend/resume
Date: Tue, 15 Jun 2021 14:39:04 +0200	[thread overview]
Message-ID: <20210615123904.2568052-3-grzegorz.jaszczyk@linaro.org> (raw)
In-Reply-To: <20210615123904.2568052-1-grzegorz.jaszczyk@linaro.org>

Suspend routine disables wdog clk. Nevertheless, the watchdog subsystem
is not aware of that and can still try to ping wdog through
watchdog_ping_work. In order to prevent such condition and therefore
prevent from system hang (caused by the wdog register access issued
while the wdog clock is disabled) take advantage of
watchdog_dev_suspend/resume routines which will take care of watchdog
ping worker cancel and restore.

Additionally remove hw ping from suspend/resume since it will be
issued by watchdog_dev_suspend/resume routines.

Signed-off-by: Michal Koziel <michal.koziel@emlogic.no>
Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
---
 drivers/watchdog/imx2_wdt.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
index b84f80f7d342..24e3a4d2b529 100644
--- a/drivers/watchdog/imx2_wdt.c
+++ b/drivers/watchdog/imx2_wdt.c
@@ -348,6 +348,17 @@ static int __maybe_unused imx2_wdt_suspend(struct device *dev)
 {
 	struct watchdog_device *wdog = dev_get_drvdata(dev);
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
+	int ret;
+
+	/*
+	 * Before disabling clk we need to notify wdog subsystem that HW wdog
+	 * is being suspended. This e.g. prevents watchdog_ping_work to fire
+	 * when the clk is disabled, which would result with system hang caused
+	 * by wdog register access while wdog clock is disabled.
+	 */
+	ret = watchdog_dev_suspend(wdog);
+	if (ret)
+		return ret;
 
 	/* The watchdog IP block is running */
 	if (imx2_wdt_is_running(wdev)) {
@@ -356,7 +367,6 @@ static int __maybe_unused imx2_wdt_suspend(struct device *dev)
 		 * during resume.
 		 */
 		__imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
-		imx2_wdt_ping(wdog);
 	}
 
 	clk_disable_unprepare(wdev->clk);
@@ -383,12 +393,12 @@ static int __maybe_unused imx2_wdt_resume(struct device *dev)
 		 */
 		imx2_wdt_setup(wdog);
 	}
-	if (imx2_wdt_is_running(wdev)) {
+	if (imx2_wdt_is_running(wdev))
 		imx2_wdt_set_timeout(wdog, wdog->timeout);
-		imx2_wdt_ping(wdog);
-	}
 
-	return 0;
+	ret = watchdog_dev_resume(wdog);
+
+	return ret;
 }
 
 static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
-- 
2.29.0


      parent reply	other threads:[~2021-06-15 12:39 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-15 12:39 [PATCH 0/2] introduce watchdog_dev_suspend/resume Grzegorz Jaszczyk
2021-06-15 12:39 ` [PATCH 1/2] watchdog: " Grzegorz Jaszczyk
2021-06-15 14:18   ` Guenter Roeck
2021-06-16 13:59     ` Grzegorz Jaszczyk
2021-06-16 17:57       ` Guenter Roeck
2021-06-16 23:21   ` kernel test robot
2021-06-15 12:39 ` Grzegorz Jaszczyk [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210615123904.2568052-3-grzegorz.jaszczyk@linaro.org \
    --to=grzegorz.jaszczyk@linaro.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-watchdog@vger.kernel.org \
    --cc=linux@roeck-us.net \
    --cc=michal.koziel@emlogic.no \
    --cc=shawnguo@kernel.org \
    --cc=wim@linux-watchdog.org \
    --subject='Re: [PATCH 2/2] watchdog: imx2_wdg: notify wdog subsystem about wdog suspend/resume' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).