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From:   Raul Rangel <rrangel@chromium.org>
Date:   Wed, 31 Aug 2022 20:17:23 -0600
Message-ID: <CAHQZ30C0Q39cSxTcfu3+6ZNj7iuRE6pJpc9aPdreFt4MNHqZRQ@mail.gmail.com>
Subject: Re: [PATCH 1/8] Input: elan_i2c - Use PM subsystem to manage wake irq
To:     Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        linux-input <linux-input@vger.kernel.org>,
        Hans de Goede <hdegoede@redhat.com>,
        Mario Limonciello <mario.limonciello@amd.com>,
        Tim Van Patten <timvp@google.com>,
        "jingle.wu" <jingle.wu@emc.com.tw>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Tony Lindgren <tony@atomide.com>
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On Wed, Aug 31, 2022 at 1:16 PM Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
>
> 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@chromium.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@chromium.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
> >

So the above entry specifies the `wake` register. This generates an
ACPI _PRW resource. The patch series will actually fix devices like
this. Today without this patch series we get two wake events for a
device. The ACPI wake GPE specified by the _PRW resource, and the
erroneous GPIO wake event. But you bring up a good point.

I wrote a quick and dirty script (https://0paste.com/391849) to parse
the coreboot device tree entries. Open source firmware is great isn't
it? ;)

$ find src/mainboard/google/ -iname '*.cb' | xargs awk -f touch.awk --
src/mainboard/google/eve/devicetree.cb
1
chip drivers/i2c/hid
register "generic.hid" = ""ACPI0C50""
register "generic.desc" = ""Touchpad""
register "generic.irq" = "ACPI_IRQ_LEVEL_LOW(GPP_B3_IRQ)"
register "hid_desc_reg_offset" = "0x1"
device i2c 49 on end
end
src/mainboard/google/eve/devicetree.cb
1
chip drivers/i2c/generic
register "hid" = ""GOOG0008""
register "desc" = ""Touchpad EC Interface""
device i2c 1e on end
end
src/mainboard/google/drallion/variants/drallion/devicetree.cb
1
chip drivers/i2c/generic
register "hid" = ""ELAN0000""
register "desc" = ""ELAN Touchpad""
register "irq" = "ACPI_IRQ_EDGE_LOW(GPP_B3_IRQ)"
register "probed" = "1"
device i2c 2c on end
end
src/mainboard/google/drallion/variants/drallion/devicetree.cb
1
chip drivers/i2c/generic
register "hid" = ""ELAN0000""
register "desc" = ""ELAN Touchpad""
register "irq" = "ACPI_IRQ_EDGE_LOW(GPP_B3_IRQ)"
register "probed" = "1"
device i2c 15 on end
end
src/mainboard/google/sarien/variants/arcada/devicetree.cb
1
chip drivers/i2c/generic
register "hid" = ""ELAN0000""
register "desc" = ""ELAN Touchpad""
register "irq" = "ACPI_IRQ_EDGE_LOW(GPP_B3_IRQ)"
register "probed" = "1"
device i2c 2c on end
end
src/mainboard/google/sarien/variants/arcada/devicetree.cb
1
chip drivers/i2c/hid
register "generic.hid" = ""PNP0C50""
register "generic.desc" = ""Cirque Touchpad""
register "generic.irq" = "ACPI_IRQ_LEVEL_LOW(GPP_B3_IRQ)"
register "generic.probed" = "1"
register "hid_desc_reg_offset" = "0x20"
device i2c 2a on end
end
src/mainboard/google/sarien/variants/sarien/devicetree.cb
1
chip drivers/i2c/generic
register "hid" = ""ELAN0000""
register "desc" = ""ELAN Touchpad""
register "irq" = "ACPI_IRQ_EDGE_LOW(GPP_B3_IRQ)"
register "probed" = "1"
device i2c 2c on end
end
Total Touchpad: 202
Total Wake: 195

Out of all the touchpads defined on ChromeOS it looks like only 4
devices are missing a wake declaration. I omitted touchpanels because
ChromeOS doesn't use those as a wake source. chromeos_laptop.c already
defines some devices with i2c board_info and it sets the
`I2C_CLIENT_WAKE` flag. I'm not sure if this is actually working as
expected. `i2c_device_probe` requires a `wakeup` irq to be present in
the device tree if the `I2C_CLIENT_WAKE` flag is set, but I'm assuming
the device tree was missing wake attributes.

Anyway, patches 6, and 7 are the ones that drop the legacy behavior. I
can figure out how to add the above boards to chromeos_laptop.c and
get the wake attribute plumbed, or I can add something directly to the
elan_i2c_core, etc so others can add overrides for their boards there.
I'll also send out CLs to fix the device tree configs (not that we
would run a FW qual just for this change).


> > 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@gmail.com>
>
> Thanks.
>
> --
> Dmitry