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

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Date:   Wed, 31 Aug 2022 20:01:12 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Raul E Rangel <rrangel@...omium.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>,
        timvp@...gle.com, "Rafael J. Wysocki" <rafael@...nel.org>,
        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 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?

> ---
>
>  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
>