linux-kernel - [PATCH] i2c: ACPI: Do not check ACPI_FADT_LOW_POWER

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Date:   Fri, 05 Aug 2022 18:51:11 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Jiri Kosina <jikos@...nel.org>
Cc:     Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        linux-input@...r.kernel.org,
        Mario Limonciello <mario.limonciello@....com>
Subject: [PATCH] i2c: ACPI: Do not check ACPI_FADT_LOW_POWER_S0

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

The ACPI_FADT_LOW_POWER_S0 flag merely means that it is better to
use low-power S0 idle on the given platform than S3 (provided that
the latter is supported) and it doesn't preclude using either of
them (which of them will be used depends on the choices made by user
space).

Because of that, ACPI_FADT_LOW_POWER_S0 is generally not sufficient
for making decisions in device drivers and so i2c_hid_acpi_probe()
should not use it.

Moreover, Linux always supports suspend-to-idle, so if a given
device can wake up the system from suspend-to-idle, then it can be
marked as wakeup capable unconditionally, so make that happen in
i2c_hid_acpi_probe().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/hid/i2c-hid/i2c-hid-acpi.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Index: linux-pm/drivers/hid/i2c-hid/i2c-hid-acpi.c
===================================================================
--- linux-pm.orig/drivers/hid/i2c-hid/i2c-hid-acpi.c
+++ linux-pm/drivers/hid/i2c-hid/i2c-hid-acpi.c
@@ -105,10 +105,8 @@ static int i2c_hid_acpi_probe(struct i2c

 	acpi_device_fix_up_power(adev);

-	if (acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0) {
-		device_set_wakeup_capable(dev, true);
-		device_set_wakeup_enable(dev, false);
-	}
+	device_set_wakeup_capable(dev, true);
+	device_set_wakeup_enable(dev, false);

 	return i2c_hid_core_probe(client, &ihid_acpi->ops,
 				  hid_descriptor_address, 0);