linux-kernel - [PATCH 1/3] HID: i2c-hid-acpi: Remove explicit device_set_wakeup

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Message-Id: <20211220163823.1.Ie20ca47a26d3ea68124d8197b67bb1344c67f650@changeid>
Date:   Mon, 20 Dec 2021 16:43:44 -0700
From:   Raul E Rangel <rrangel@...omium.org>
To:     linux-kernel@...r.kernel.org
Cc:     mario.limonciello@....com, linux-input@...r.kernel.org,
        dianders@...omium.org, Raul E Rangel <rrangel@...omium.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Jiri Kosina <jikos@...nel.org>
Subject: [PATCH 1/3] HID: i2c-hid-acpi: Remove explicit device_set_wakeup_capable

The ACPI subsystem is responsible for managing the power and wake
sources for an ACPI device. By explicitly calling
device_set_wakeup_capable, we are circumvent the ACPI subsystem and
setting wake capabilities on the device when it doesn't support it.

Take the following example:
* We have an ACPI HID device that has `_PR0` and `_PR3`. It doesn't have
`_PRW` so that means the device can't wake the system.
* The IRQ line is active level low for this device and is pulled up by the
power resource defined in `_PR0`/`_PR3`.

Since the i2c-hid driver has set the device as wake capable, the wake
pin gets enabled on suspend. As part of suspend, ACPI will power down
the device since it's not a wake source. When the device is powered
down, the IRQ line will drop, and it will trigger a wake event.

See the following debug log:
[   42.335804] PM: Suspending system (s2idle)
[   42.340186] amd_gpio AMD0030:00: RX: Setting wake for pin 89 to enable
[   42.467736]     power-0416 __acpi_power_off      : Power resource [PR00] turned off
[   42.467739] device_pm-0280 device_set_power      : Device [H05D] transitioned to D3cold
[   42.475210] PM: pm_system_irq_wakeup: 11 triggered pinctrl_amd
[   42.535293] PM: Wakeup unrelated to ACPI SCI
[   42.535294] PM: resume from suspend-to-idle

Signed-off-by: Raul E Rangel <rrangel@...omium.org>
---

 drivers/hid/i2c-hid/i2c-hid-acpi.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid-acpi.c b/drivers/hid/i2c-hid/i2c-hid-acpi.c
index a6f0257a26de..fc311a19a19d 100644
--- a/drivers/hid/i2c-hid/i2c-hid-acpi.c
+++ b/drivers/hid/i2c-hid/i2c-hid-acpi.c
@@ -105,11 +105,6 @@ static int i2c_hid_acpi_probe(struct i2c_client *client)

 	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);
-	}
-
 	return i2c_hid_core_probe(client, &ihid_acpi->ops,
 				  hid_descriptor_address);
 }
-- 
2.34.1.307.g9b7440fafd-goog