Patch "watchdog: rti_wdt: Drop runtime pm reference count when watchdog is unused" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    watchdog: rti_wdt: Drop runtime pm reference count when watchdog is unused

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     watchdog-rti_wdt-drop-runtime-pm-reference-count-whe.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 823429dadc6322f8c969c665b8e9b7a46cc3a884
Author: Vignesh Raghavendra <vigneshr@xxxxxx>
Date:   Wed Dec 13 19:31:10 2023 +0530

    watchdog: rti_wdt: Drop runtime pm reference count when watchdog is unused
    
    [ Upstream commit c1a6edf3b541e44e78f10bc6024df779715723f1 ]
    
    Call runtime_pm_put*() if watchdog is not already started during probe and re
    enable it in watchdog start as required.
    
    On K3 SoCs, watchdogs and their corresponding CPUs are under same
    power-domain, 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 power-domain due to dangling
    reference count.
    
    Fixes: 2d63908bdbfb ("watchdog: Add K3 RTI watchdog support")
    Signed-off-by: Vignesh Raghavendra <vigneshr@xxxxxx>
    Tested-by: Manorit Chawdhry <m-chawdhry@xxxxxx>
    Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20231213140110.938129-1-vigneshr@xxxxxx
    Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
    Signed-off-by: Wim Van Sebroeck <wim@xxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
index 46c2a4bd9ebe..daa00f3c5a6a 100644
--- a/drivers/watchdog/rti_wdt.c
+++ b/drivers/watchdog/rti_wdt.c
@@ -70,6 +70,11 @@ 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;
@@ -296,6 +301,9 @@ 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:
@@ -310,7 +318,10 @@ static int 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);
 
 	return 0;