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

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