Re: [PATCH 1/2] Input: atmel_mxt_ts: Add wake-up support

[Loic Poulain <loic.poulain@linaro.org>]

Hi Dmitry,

On Thu, 24 Jun 2021 at 02:41, Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
>
> Hi Loic,
>
> On Wed, Jun 23, 2021 at 03:56:36PM +0200, Loic Poulain wrote:
> > Add capability for the touchscreen to wakeup the host on touch event.
> >
> > Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> > ---
> >  drivers/input/touchscreen/atmel_mxt_ts.c | 18 ++++++++++++++----
> >  1 file changed, 14 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> > index 05de92c..807f449 100644
> > --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> > +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> > @@ -3223,6 +3223,8 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
> >               return error;
> >       }
> >
> > +     device_set_wakeup_capable(&client->dev, true);
>
> We do not want to make the touch controller be wakeup source
> unconditionally. I2C core recognized "wakeup-source" in device tree,
> other platforms may employ different techniques setting I2C_CLIENT_WAKE
> when registering I2C devices to mark them as wakeup capable/enabled.

Contrary to device_init_wakeup(), used in some other input drivers,
device_set_wakeup_capable() does not enable the device as a wakeup
source but just sets it as wakeup capable, and it's up to the user or
distro policy to enable it as a wakeup source or not. It's a quite
common way to do, and it does not change the behavior of this driver.
The I2C_CLIENT_WAKE forces enabling wakeup source, which is maybe not
what we want by default for a touchscreen. remote-wakeup enabling is a
device configuration not a hardware property. Thoughts?

I should probably also add dev_pm_set_wake_irq() for auto-enabling
wake on suspend instead of doing it manually.

Regards,
Loic