linux-kernel - [PATCH v2] watchdog: rti_wdt: Drop RPM count when unused

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Message-ID: <20231122041642.2015936-1-vigneshr@ti.com>
Date:   Wed, 22 Nov 2023 09:46:42 +0530
From:   Vignesh Raghavendra <vigneshr@...com>
To:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>
CC:     Tero Kristo <kristo@...nel.org>, <linux-watchdog@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        <linux-arm-kernel@...ts.infradead.org>, <afd@...com>
Subject: [PATCH v2] watchdog: rti_wdt: Drop RPM count when unused

Do a RPM put if watchdog is not already started during probe and re
enable it in watchdog start.

On K3 SoCs, watchdogs and their corresponding CPUs are under same PD, so
if the reference count of unused watchdogs aren't dropped, it will lead
to CPU hotplug failures as Device Management firmware won't allow to
turn off the PD due to dangling reference count.

Fixes: 2d63908bdbfb ("watchdog: Add K3 RTI watchdog support")
Signed-off-by: Vignesh Raghavendra <vigneshr@...com>
---

v2:
* Drop 1/2 (will be posted along with runtime_pm callbacks)
* Use pm_runtime_resume_and_get() instead of pm_runtime_get_sync() which
 takes care of err handling

v1: lore.kernel.org/r/20231110100726.2930218-1-vigneshr@...com

 drivers/watchdog/rti_wdt.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
index 8e1be7ba0103..9215793a1c81 100644
--- a/drivers/watchdog/rti_wdt.c
+++ b/drivers/watchdog/rti_wdt.c
@@ -77,6 +77,11 @@ static int rti_wdt_start(struct watchdog_device *wdd)
 {
 	u32 timer_margin;
 	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(wdd->parent);
+	if (ret)
+		return ret;
 
 	/* set timeout period */
 	timer_margin = (u64)wdd->timeout * wdt->freq;
@@ -343,6 +348,9 @@ static int rti_wdt_probe(struct platform_device *pdev)
 	if (last_ping)
 		watchdog_set_last_hw_keepalive(wdd, last_ping);
 
+	if (!watchdog_hw_running(wdd))
+		pm_runtime_put_sync(&pdev->dev);
+
 	return 0;
 
 err_iomap:
@@ -357,7 +365,10 @@ static void rti_wdt_remove(struct platform_device *pdev)
 	struct rti_wdt_device *wdt = platform_get_drvdata(pdev);
 
 	watchdog_unregister_device(&wdt->wdd);
-	pm_runtime_put(&pdev->dev);
+
+	if (!pm_runtime_suspended(&pdev->dev))
+		pm_runtime_put(&pdev->dev);
+
 	pm_runtime_disable(&pdev->dev);
 }
 
-- 
2.42.0