linux-kernel - Re: [PATCH 1/8] Input: elan_i2c - Use PM subsystem to manage wake irq

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Message-ID: <Yw+yqbaTi04Ydgkq@google.com>
Date:   Wed, 31 Aug 2022 12:12:41 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Raul E Rangel <rrangel@...omium.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        linux-input <linux-input@...r.kernel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Mario Limonciello <mario.limonciello@....com>,
        timvp@...gle.com, "jingle.wu" <jingle.wu@....com.tw>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Tony Lindgren <tony@...mide.com>
Subject: Re: [PATCH 1/8] Input: elan_i2c - Use PM subsystem to manage wake irq

On Wed, Aug 31, 2022 at 08:01:12PM +0200, Rafael J. Wysocki wrote:
> On Wed, Aug 31, 2022 at 1:16 AM Raul E Rangel <rrangel@...omium.org> wrote:
> >
> > The Elan I2C touchpad driver is currently manually managing the wake
> > IRQ. This change removes the explicit enable_irq_wake/disable_irq_wake
> > and instead relies on the PM subsystem. This is done by calling
> > dev_pm_set_wake_irq.
> >
> > i2c_device_probe already calls dev_pm_set_wake_irq when using device
> > tree, so it's only required when using ACPI. The net result is that this
> > change should be a no-op. i2c_device_remove also already calls
> > dev_pm_clear_wake_irq, so we don't need to do that in this driver.
> >
> > I tested this on an ACPI system where the touchpad doesn't have _PRW
> > defined. I verified I can still wake the system and that the wake source
> > was the touchpad IRQ GPIO.
> >
> > Signed-off-by: Raul E Rangel <rrangel@...omium.org>
> 
> I like this a lot [...]

I also like this a lot, but this assumes that firmware has correct
settings for the interrupt... Unfortunately it is not always the case
and I see that at least Chrome OS devices, such as glados line (cave, chell, sentry,
ect) do not mark interrupt as wakeup:

src/mainboard/google/glados/variants/chell/overridetree.cb

                        chip drivers/i2c/generic
                                register "hid" = ""ELAN0000""
                                register "desc" = ""ELAN Touchpad""
                                register "irq" = "ACPI_IRQ_LEVEL_LOW(GPP_B3_IRQ)"
                                register "wake" = "GPE0_DW0_05"
                                device i2c 15 on end

I assume it should have been ACPI_IRQ_WAKE_LEVEL_LOW for the interrupt
to be marked as wakeup.

(we do correctly mark GPE as wakeup).

So we need to do something about older devices....

-- 
Dmitry