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

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Message-ID: <CAHQZ30BTYEYEAGjwsbuiYuYGhpFtQy_AEP66v3trdTzY_DRUOQ@mail.gmail.com>
Date:   Wed, 31 Aug 2022 12:13:46 -0600
From:   Raul Rangel <rrangel@...omium.org>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        linux-input <linux-input@...r.kernel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Mario Limonciello <mario.limonciello@....com>,
        Tim Van Patten <timvp@...gle.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        "jingle.wu" <jingle.wu@....com.tw>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Tony Lindgren <tony@...mide.com>
Subject: Re: [PATCH 1/8] Input: elan_i2c - Use PM subsystem to manage wake irq

On Wed, Aug 31, 2022 at 12:01 PM Rafael J. Wysocki <rafael@...nel.org> wrote:
>
> On Wed, Aug 31, 2022 at 1:16 AM Raul E Rangel <rrangel@...omium.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@...omium.org>
>


> I like this a lot, but the assumption in the wakeirq code is that the
> IRQ in question will be dedicated for signaling wakeup.  Does it hold
> here?

The wakeirq code defines two methods: `dev_pm_set_wake_irq` and
`dev_pm_set_dedicated_wake_irq`.
The latter is used when you have a dedicated wakeup signal. In this
driver it's currently assumed
that the IRQ and the wake IRQ are the same, so I used `dev_pm_set_wake_irq`.

This change in theory also fixes a bug where you define a dedicated
wake irq in DT, but
then the driver enables the `client->irq` as a wake source. In
practice this doesn't happen
since the elan touchpads only have a single IRQ line.

>
> > ---
> >
> >  drivers/input/mouse/elan_i2c_core.c | 12 ++++--------
> >  1 file changed, 4 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/input/mouse/elan_i2c_core.c b/drivers/input/mouse/elan_i2c_core.c
> > index e1758d5ffe4218..7d997d2b56436b 100644
> > --- a/drivers/input/mouse/elan_i2c_core.c
> > +++ b/drivers/input/mouse/elan_i2c_core.c
> > @@ -33,6 +33,7 @@
> >  #include <linux/jiffies.h>
> >  #include <linux/completion.h>
> >  #include <linux/of.h>
> > +#include <linux/pm_wakeirq.h>
> >  #include <linux/property.h>
> >  #include <linux/regulator/consumer.h>
> >  #include <asm/unaligned.h>
> > @@ -86,8 +87,6 @@ struct elan_tp_data {
> >         u16                     fw_page_size;
> >         u32                     fw_signature_address;
> >
> > -       bool                    irq_wake;
> > -
> >         u8                      min_baseline;
> >         u8                      max_baseline;
> >         bool                    baseline_ready;
> > @@ -1337,8 +1336,10 @@ static int elan_probe(struct i2c_client *client,
> >          * Systems using device tree should set up wakeup via DTS,
> >          * the rest will configure device as wakeup source by default.
> >          */
> > -       if (!dev->of_node)
> > +       if (!dev->of_node) {
> >                 device_init_wakeup(dev, true);
> > +               dev_pm_set_wake_irq(dev, client->irq);
> > +       }
> >
> >         return 0;
> >  }
> > @@ -1362,8 +1363,6 @@ static int __maybe_unused elan_suspend(struct device *dev)
> >
> >         if (device_may_wakeup(dev)) {
> >                 ret = elan_sleep(data);
> > -               /* Enable wake from IRQ */
> > -               data->irq_wake = (enable_irq_wake(client->irq) == 0);
> >         } else {
> >                 ret = elan_set_power(data, false);
> >                 if (ret)
> > @@ -1394,9 +1393,6 @@ static int __maybe_unused elan_resume(struct device *dev)
> >                         dev_err(dev, "error %d enabling regulator\n", error);
> >                         goto err;
> >                 }
> > -       } else if (data->irq_wake) {
> > -               disable_irq_wake(client->irq);
> > -               data->irq_wake = false;
> >         }
> >
> >         error = elan_set_power(data, true);
> > --
> > 2.37.2.672.g94769d06f0-goog
> >