linux-kernel - [PATCH 2/2] clocksource/drivers/timer-tegra186: fix watchdog self-pinging.

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Message-ID: <20240116115838.16544-3-pohsuns@nvidia.com>
Date: Tue, 16 Jan 2024 19:58:38 +0800
From: Pohsun Su <pohsuns@...dia.com>
To: <daniel.lezcano@...aro.org>, <tglx@...utronix.de>,
	<thierry.reding@...il.com>, <jonathanh@...dia.com>
CC: <sumitg@...dia.com>, <linux-kernel@...r.kernel.org>,
	<linux-tegra@...r.kernel.org>, Pohsun Su <pohsuns@...dia.com>
Subject: [PATCH 2/2] clocksource/drivers/timer-tegra186: fix watchdog self-pinging.

This change removes watchdog self-pinging behavior.

The timer irq handler is triggered due to the 1st expiration,
the handler disables and enables watchdog but also implicitly
clears the expiration count so the count can only be 0 or 1.

Since this watchdog supports opened, configured, or pinged by
systemd, We remove this behavior or the watchdog may not bark
when systemd crashes since the 5th expiration never comes.

Signed-off-by: Pohsun Su <pohsuns@...dia.com>
---
 drivers/clocksource/timer-tegra186.c | 24 ++----------------------
 1 file changed, 2 insertions(+), 22 deletions(-)

diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
index 685c6689a2da..963c12c81f4d 100644
--- a/drivers/clocksource/timer-tegra186.c
+++ b/drivers/clocksource/timer-tegra186.c
@@ -174,7 +174,8 @@ static void tegra186_wdt_enable(struct tegra186_wdt *wdt)
 		value |= WDTCR_PERIOD(1);
 
 		/* enable local interrupt for WDT petting */
-		value |= WDTCR_LOCAL_INT_ENABLE;
+		if (0)
+			value |= WDTCR_LOCAL_INT_ENABLE;
 
 		/* enable local FIQ and remote interrupt for debug dump */
 		if (0)
@@ -406,18 +407,6 @@ static int tegra186_timer_usec_init(struct tegra186_timer *tegra)
 	return clocksource_register_hz(&tegra->usec, USEC_PER_SEC);
 }
 
-static irqreturn_t tegra186_timer_irq(int irq, void *data)
-{
-	struct tegra186_timer *tegra = data;
-
-	if (watchdog_active(&tegra->wdt->base)) {
-		tegra186_wdt_disable(tegra->wdt);
-		tegra186_wdt_enable(tegra->wdt);
-	}
-
-	return IRQ_HANDLED;
-}
-
 static int tegra186_timer_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -469,17 +458,8 @@ static int tegra186_timer_probe(struct platform_device *pdev)
 		goto unregister_osc;
 	}
 
-	err = devm_request_irq(dev, irq, tegra186_timer_irq, 0,
-			       "tegra186-timer", tegra);
-	if (err < 0) {
-		dev_err(dev, "failed to request IRQ#%u: %d\n", irq, err);
-		goto unregister_usec;
-	}
-
 	return 0;
 
-unregister_usec:
-	clocksource_unregister(&tegra->usec);
 unregister_osc:
 	clocksource_unregister(&tegra->osc);
 unregister_tsc:
-- 
2.17.1