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    SubjectRe: [PATCH 1/8] Input: elan_i2c - Use PM subsystem to manage wake irq
    On Fri, Sep 2, 2022 at 11:07 PM Dmitry Torokhov
    <dmitry.torokhov@gmail.com> wrote:
    >
    > On Wed, Aug 31, 2022 at 08:17:23PM -0600, Raul Rangel wrote:
    > > 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.
    >


    > Does this mean that the example that we currently have in coreboot
    > documentation (Documentation/acpi/devicetree.md) is not correct:
    >
    > device pci 15.0 on
    > chip drivers/i2c/generic
    > register "hid" = ""ELAN0000""
    > register "desc" = ""ELAN Touchpad""
    > register "irq" = "ACPI_IRQ_WAKE_LEVEL_LOW(GPP_A21_IRQ)"
    > register "wake" = "GPE0_DW0_21"
    > device i2c 15 on end
    > end
    > end # I2C #0
    >
    > Doesn't in say that we have both GpioIrq and GPE wakeup methods defined
    > for the same device?

    Hrmm, yeah that is wrong and will cause duplicate wake events for the
    device. I'll push a CL to clean up the documentation.

    >
    > >
    > > 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
    >
    > ...
    >
    > > 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
    >
    > No it does not. If there is no wakeup IRQ defined of_irq_get_byname()
    > will return an error and we'll take the "else if (client->irq > 0)"
    > branch and will set up client->irq as the wakeup irq.
    >
    > > the device tree was missing wake attributes.

    Oh thanks for pointing that out. I might refactor patch #4 to just set
    the `I2C_CLIENT_WAKE` flag when `acpi_wake_capable` is true.

    >
    > >
    > > 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).
    >
    > My preference is to limit board-specific hacks in drivers if we can, so
    > adding missing properties to chromeos_laptop.c would be my preference.

    How should we handle non chromeos boards?

    >
    > Thanks.
    >
    > --
    > Dmitry

    Thanks!

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