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

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Message-ID: <Yxf8F4mO8XUW0keq@google.com>
Date:   Tue, 6 Sep 2022 19:04:07 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Raul Rangel <rrangel@...omium.org>
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 06, 2022 at 08:00:00PM -0600, Raul Rangel wrote:
> 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?

I've heard there are ARM ACPI systems...

Thanks.

-- 
Dmitry