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

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Message-ID: <Yw+zo9eUQM+T1eYZ@google.com>
Date:   Wed, 31 Aug 2022 12:16:51 -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 12:12:41PM -0700, Dmitry Torokhov wrote:
> 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....

After re-reading the patch I believe this comment is more applicable to
the followup patch to elan_i2c, not this one, which is fine on its own.

Acked-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

Thanks.

-- 
Dmitry