linux-kernel - Re: [PATCH 4/8] i2c: acpi: Use ACPI GPIO wake capability bit to set wake

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Date:   Tue, 6 Sep 2022 20:00:00 -0600
From:   Raul Rangel <rrangel@...omium.org>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Linux ACPI <linux-acpi@...r.kernel.org>,
        linux-input <linux-input@...r.kernel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        "Limonciello, Mario" <mario.limonciello@....com>,
        Tim Van Patten <timvp@...gle.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Wolfram Sang <wsa@...nel.org>,
        "open list:I2C SUBSYSTEM HOST DRIVERS" <linux-i2c@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/8] i2c: acpi: Use ACPI GPIO wake capability bit to set wake_irq

On Tue, Sep 6, 2022 at 7:00 PM Dmitry Torokhov
<dmitry.torokhov@...il.com> wrote:
>
> On Tue, Aug 30, 2022 at 05:15:37PM -0600, Raul E Rangel wrote:
> > Device tree already has a mechanism to pass the wake_irq. It does this
> > by looking for the wakeup-source property and setting the
> > I2C_CLIENT_WAKE flag. This CL adds the ACPI equivalent. It uses at the
> > ACPI GpioInt wake flag to determine if the interrupt can be used to wake
> > the system. Previously the i2c drivers had to make assumptions and
> > blindly enable the wake IRQ. This can cause spurious wake events. e.g.,
> > If there is a device with an Active Low interrupt and the device gets
> > powered off while suspending, the interrupt line will go low since it's
> > no longer powered and wake the system. For this reason we should respect
> > the board designers wishes and honor the wake bit defined on the
> > GpioInt.
> >
> > This change does not cover the ACPI Interrupt or IRQ resources.
> >
> > Signed-off-by: Raul E Rangel <rrangel@...omium.org>
> > ---
> >
> >  drivers/i2c/i2c-core-acpi.c |  8 ++++++--
> >  drivers/i2c/i2c-core-base.c | 17 +++++++++++------
> >  drivers/i2c/i2c-core.h      |  4 ++--
> >  3 files changed, 19 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
> > index c762a879c4cc6b..cfe82a6ba3ef28 100644
> > --- a/drivers/i2c/i2c-core-acpi.c
> > +++ b/drivers/i2c/i2c-core-acpi.c
> > @@ -182,12 +182,13 @@ static int i2c_acpi_add_resource(struct acpi_resource *ares, void *data)
> >  /**
> >   * i2c_acpi_get_irq - get device IRQ number from ACPI
> >   * @client: Pointer to the I2C client device
> > + * @wake_capable: Set to 1 if the IRQ is wake capable
> >   *
> >   * Find the IRQ number used by a specific client device.
> >   *
> >   * Return: The IRQ number or an error code.
> >   */
> > -int i2c_acpi_get_irq(struct i2c_client *client)
> > +int i2c_acpi_get_irq(struct i2c_client *client, int *wake_capable)
> >  {
> >       struct acpi_device *adev = ACPI_COMPANION(&client->dev);
> >       struct list_head resource_list;
> > @@ -196,6 +197,9 @@ int i2c_acpi_get_irq(struct i2c_client *client)
> >
> >       INIT_LIST_HEAD(&resource_list);
> >
> > +     if (wake_capable)
> > +             *wake_capable = 0;
> > +
> >       ret = acpi_dev_get_resources(adev, &resource_list,
> >                                    i2c_acpi_add_resource, &irq);
>


> You also need to handle "Interrupt(..., ...AndWake)" case here. I would
> look into maybe defining
>
> #define IORESOURCE_IRQ_WAKECAPABLE      (1<<6)
>
> in include/linux/ioport.h and plumbing it through from ACPI layer.
>
> Thanks.

AFAIK the Intel (Not 100% certain) and AMD IO-APIC's can't actually
wake a system from suspend/suspend-to-idle. It requires either a GPE
or GPIO controller to wake the system. This is the reason I haven't
pushed patches to handle the Interrupt/IRQ resource. Can anyone
confirm?

Thanks

>
> --
> Dmitry