linux-kernel - Re: [RFC PATCH 2/2] i2c: attach/detach I2C client device to the ACPI power domain

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Date:	Tue, 20 Aug 2013 16:16:46 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:	linux-i2c@...r.kernel.org, Wolfram Sang <wsa@...-dreams.de>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	Lv Zheng <lv.zheng@...el.com>, Aaron Lu <aaron.lu@...el.com>
Subject: Re: [RFC PATCH 2/2] i2c: attach/detach I2C client device to the ACPI power domain

On Tuesday, August 20, 2013 05:03:36 PM Mika Westerberg wrote:
> From: Lv Zheng <lv.zheng@...el.com>
> 
> If the I2C client device is enumerated from ACPI namespace it might have
> ACPI methods that needs to be called in order to transition the device to
> a different power states (such as _PSx).
> 
> Implement this for I2C client devices by checking if the device has an ACPI
> handle and if that's the case, attach it to the ACPI power domain. In
> addition we make sure that the device is fully powered when its ->probe()
> function gets called.
> 
> For non-ACPI devices this patch is a no-op.
> 
> Signed-off-by: Lv Zheng <lv.zheng@...el.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
>  drivers/i2c/i2c-core.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index 8fad5ac..fdf086b 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -257,6 +257,9 @@ static int i2c_device_probe(struct device *dev)
>  	/* Make sure the adapter is active */
>  	pm_runtime_get_sync(&client->adapter->dev);
>  
> +	if (ACPI_HANDLE(&client->dev))
> +		acpi_dev_pm_attach(&client->dev, true);
> +
>  	/*
>  	 * Enable runtime PM for the client device. If the client wants to
>  	 * participate on runtime PM it should call pm_runtime_put() in its
> @@ -278,6 +281,9 @@ static int i2c_device_probe(struct device *dev)
>  		pm_runtime_disable(&client->dev);
>  		pm_runtime_set_suspended(&client->dev);
>  		pm_runtime_put_noidle(&client->dev);
> +
> +		if (ACPI_HANDLE(&client->dev))
> +			acpi_dev_pm_detach(&client->dev, true);
>  	}
>  
>  	pm_runtime_put(&client->adapter->dev);
> @@ -314,6 +320,9 @@ static int i2c_device_remove(struct device *dev)
>  	pm_runtime_set_suspended(&client->dev);
>  	pm_runtime_put_noidle(&client->dev);
>  
> +	if (ACPI_HANDLE(&client->dev))
> +		acpi_dev_pm_detach(&client->dev, true);
> +
>  	pm_runtime_put(&client->adapter->dev);
>  	return status;
>  }
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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