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 18:00:37 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Raul E Rangel <rrangel@...omium.org>
Cc:     linux-acpi@...r.kernel.org, linux-input@...r.kernel.org,
        hdegoede@...hat.com, mario.limonciello@....com, timvp@...gle.com,
        rafael@...nel.org,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Wolfram Sang <wsa@...nel.org>, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/8] i2c: acpi: Use ACPI GPIO wake capability bit to set
 wake_irq

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.

-- 
Dmitry