linux-kernel - [PATCH 1/2] ACPI: PM: Avoid evaluating _PS3 on transitions from D3hot to D3cold

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Date:   Tue, 25 Jun 2019 14:04:45 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux ACPI <linux-acpi@...r.kernel.org>
Cc:     Bjorn Helgaas <helgaas@...nel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Zhang Rui <rui.zhang@...el.com>
Subject: [PATCH 1/2] ACPI: PM: Avoid evaluating _PS3 on transitions from D3hot to D3cold

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

If the power state of a device with ACPI PM is changed from D3hot to
D3cold, it merely is a matter of dropping references to additional
power resources (specifically, those in the list returned by _PR3),
and the _PS3 method should not be invoked for the device then (as
it has already been evaluated during the previous transition to
D3hot).

Fixes: 20dacb71ad28 (ACPI / PM: Rework device power management to follow ACPI 6)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/acpi/device_pm.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

Index: linux-pm/drivers/acpi/device_pm.c
===================================================================
--- linux-pm.orig/drivers/acpi/device_pm.c
+++ linux-pm/drivers/acpi/device_pm.c
@@ -215,9 +215,15 @@ int acpi_device_set_power(struct acpi_de
 			return -ENODEV;
 		}
 
-		result = acpi_dev_pm_explicit_set(device, state);
-		if (result)
-			goto end;
+		/*
+		 * If the device goes from D3hot to D3cold, _PS3 has been
+		 * evaluated for it already, so skip it in that case.
+		 */
+		if (device->power.state < ACPI_STATE_D3_HOT) {
+			result = acpi_dev_pm_explicit_set(device, state);
+			if (result)
+				goto end;
+		}
 
 		if (device->power.flags.power_resources)
 			result = acpi_power_transition(device, target_state);