linux-kernel - [PATCH v1 1/2] ACPI: PM: Do not turn off power resources in unknown state

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Date:   Fri, 15 Oct 2021 19:12:21 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux ACPI <linux-acpi@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linux PCI <linux-pci@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "Andreas K. Huettel" <andreas.huettel@...de>
Subject: [PATCH v1 1/2] ACPI: PM: Do not turn off power resources in unknown state

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Commit 6381195ad7d0 ("ACPI: power: Rework turning off unused power
resources") caused power resources in unknown state with reference
counters equal to zero to be turned off too, but that caused issues
to appear in the field, so modify the code to only turn off power
resources that are known to be "on".

Link: https://lore.kernel.org/linux-acpi/6faf4b92-78d5-47a4-63df-cc2bab7769d0@molgen.mpg.de/
Fixes: 6381195ad7d0 ("ACPI: power: Rework turning off unused power resources")
Reported-by: Andreas K. Huettel <andreas.huettel@...de>
Tested-by: Andreas K. Huettel <andreas.huettel@...de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Cc: 5.14+ <stable@...r.kernel.org> # 5.14+
---
 drivers/acpi/power.c |    7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

Index: linux-pm/drivers/acpi/power.c
===================================================================
--- linux-pm.orig/drivers/acpi/power.c
+++ linux-pm/drivers/acpi/power.c
@@ -1015,13 +1015,8 @@ void acpi_turn_off_unused_power_resource
 	list_for_each_entry_reverse(resource, &acpi_power_resource_list, list_node) {
 		mutex_lock(&resource->resource_lock);
 
-		/*
-		 * Turn off power resources in an unknown state too, because the
-		 * platform firmware on some system expects the OS to turn off
-		 * power resources without any users unconditionally.
-		 */
 		if (!resource->ref_count &&
-		    resource->state != ACPI_POWER_RESOURCE_STATE_OFF) {
+		    resource->state == ACPI_POWER_RESOURCE_STATE_ON) {
 			acpi_handle_debug(resource->device.handle, "Turning OFF\n");
 			__acpi_power_off(resource);
 		}