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:

quoted

On Wed, Aug 31, 2022 at 1:16 AM Raul E Rangel [off-list ref] wrote:

quoted

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 <redacted>

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@gmail.com>

Thanks.

-- 
Dmitry