Re: [PATCH v3 07/13] i2c: acpi: Use ACPI wake capability bit to set wake_irq

[Raul Rangel]

On Thu, Sep 15, 2022 at 4:46 AM Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
>
> On Wed, Sep 14, 2022 at 05:57:55PM -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 the
> > ACPI interrupt 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 wakes the system. For this reason we should
> > respect the board designers wishes and honor the wake bit defined on the
> > interrupt.
> >
> > Signed-off-by: Raul E Rangel <rrangel@xxxxxxxxxxxx>
> > ---
> >
> > Changes in v3:
> > - Convert wake_capable to bool
> > - Only update wake_capable pointer once
> > - Move wake_capable local into local block
> >
> > Changes in v2:
> > - Look at wake_cabple bit for IRQ/Interrupt resources
> >
> >  drivers/i2c/i2c-core-acpi.c | 33 ++++++++++++++++++++++++---------
> >  drivers/i2c/i2c-core-base.c |  8 +++++++-
> >  drivers/i2c/i2c-core.h      |  4 ++--
> >  3 files changed, 33 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
> > index c762a879c4cc6b..b3d68a9659ff4f 100644
> > --- a/drivers/i2c/i2c-core-acpi.c
> > +++ b/drivers/i2c/i2c-core-acpi.c
> > @@ -137,6 +137,11 @@ static const struct acpi_device_id i2c_acpi_ignored_device_ids[] = {
> >       {}
> >  };
> >
> > +struct i2c_acpi_irq_context {
> > +     int irq;
> > +     bool wake_capable;
> > +};
> > +
> >  static int i2c_acpi_do_lookup(struct acpi_device *adev,
> >                             struct i2c_acpi_lookup *lookup)
> >  {
> > @@ -170,11 +175,14 @@ static int i2c_acpi_do_lookup(struct acpi_device *adev,
> >
> >  static int i2c_acpi_add_resource(struct acpi_resource *ares, void *data)
> >  {
> > -     int *irq = data;
> > +     struct i2c_acpi_irq_context *irq_ctx = data;
> >       struct resource r;
> >

> > -     if (*irq <= 0 && acpi_dev_resource_interrupt(ares, 0, &r))
> > -             *irq = i2c_dev_irq_from_resources(&r, 1);
> > +     if (irq_ctx->irq <= 0 && acpi_dev_resource_interrupt(ares, 0, &r)) {
> > +             irq_ctx->irq = i2c_dev_irq_from_resources(&r, 1);
> > +             irq_ctx->wake_capable =
> > +                     !!(r.flags & IORESOURCE_IRQ_WAKECAPABLE);
>
> You don't need the !!() here. Just
>
>                 irq_ctx->wake_capable = r.flags & IORESOURCE_IRQ_WAKECAPABLE;
>
You know, I learned something new today! I was concerned about this
setting `wake_capable` to something that wasn't 0 or 1, but apparently
this is handled by the compiler!

http://port70.net/~nsz/c/c11/n1570.html#6.3.1.2

> 6.3.1.2 Boolean type
> When any scalar value is converted to _Bool, the result is 0 if the value compares equal to 0; otherwise, the result is 1.

Whoah!

> > +     }
> >
> >       return 1; /* No need to add resource to the list */
> >  }
> > @@ -182,31 +190,38 @@ 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 true 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, bool *wake_capable)
> >  {
> >       struct acpi_device *adev = ACPI_COMPANION(&client->dev);
> >       struct list_head resource_list;
> > -     int irq = -ENOENT;
> > +     struct i2c_acpi_irq_context irq_ctx = {
> > +             .irq = -ENOENT,
> > +     };
> >       int ret;
> >
> >       INIT_LIST_HEAD(&resource_list);
> >
> >       ret = acpi_dev_get_resources(adev, &resource_list,
> > -                                  i2c_acpi_add_resource, &irq);
> > +                                  i2c_acpi_add_resource, &irq_ctx);
> >       if (ret < 0)
> >               return ret;
> >
> >       acpi_dev_free_resource_list(&resource_list);
> >
> > -     if (irq == -ENOENT)
> > -             irq = acpi_dev_gpio_irq_get(adev, 0);
> > +     if (irq_ctx.irq == -ENOENT)
> > +             irq_ctx.irq = acpi_dev_gpio_irq_wake_get(adev, 0,
> > +                                                      &irq_ctx.wake_capable);
> > +
> > +     if (wake_capable)
> > +             *wake_capable = irq_ctx.wake_capable;
> >
> > -     return irq;
> > +     return irq_ctx.irq;
> >  }
> >
> >  static int i2c_acpi_get_info(struct acpi_device *adev,
> > diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> > index 91007558bcb260..c4debd46c6340f 100644
> > --- a/drivers/i2c/i2c-core-base.c
> > +++ b/drivers/i2c/i2c-core-base.c
> > @@ -487,8 +487,14 @@ static int i2c_device_probe(struct device *dev)
> >                       if (irq == -EINVAL || irq == -ENODATA)
> >                               irq = of_irq_get(dev->of_node, 0);
> >               } else if (ACPI_COMPANION(dev)) {
> > -                     irq = i2c_acpi_get_irq(client);
> > +                     bool wake_capable;
> > +
> > +                     irq = i2c_acpi_get_irq(client, &wake_capable);
> > +
>
> Drop the empty line here.
Done

>
> > +                     if (irq > 0 && wake_capable)
> > +                             client->flags |= I2C_CLIENT_WAKE;
> >               }
> > +
>
> Unrelated whitespace change.
Done

>
> With those fixed feel free to add,
>
> Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>

Added, thanks!