linux-kernel - Re: [PATCH 5/7] ACPI / PM: Provide device PM functions operating on struct acpi

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Message-ID: <20121030072844.GA6154@aaronlu.sh.intel.com>
Date:	Tue, 30 Oct 2012 15:28:45 +0800
From:	Aaron Lu <aaron.lu@...el.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Linux PM list <linux-pm@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Huang Ying <ying.huang@...el.com>,
	LKML <linux-kernel@...r.kernel.org>, Len Brown <lenb@...nel.org>,
	Lv Zheng <lv.zheng@...el.com>,
	Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH 5/7] ACPI / PM: Provide device PM functions operating on
 struct acpi_device

On Mon, Oct 29, 2012 at 10:11:20AM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> If the caller of acpi_bus_set_power() already has a pointer to the
> struct acpi_device object corresponding to the device in question, it
> doesn't make sense for it to go through acpi_bus_get_device(), which
> may be costly, because it involves acquiring the global ACPI
> namespace mutex.
> 
> For this reason, export the function operating on struct acpi_device
> objects used internally by acpi_bus_set_power(), so that it may be
> called instead of acpi_bus_set_power() in the above case, and change
> its name to acpi_device_set_power().
> 
> Additionally, introduce two inline wrappers for checking ACPI PM
> capabilities of devices represented by struct acpi_device objects.

What about adding yet another wrapper to check power off capability of
the device? If device has _PS3 or _PRx, it means the device can be
powered off from ACPI's perspective. This is useful for ZPODD when
deciding if platform has the required ability to support it.

Thanks,
Aaron

> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/acpi/bus.c      |   15 ++++++++++++---
>  include/acpi/acpi_bus.h |   11 +++++++++++
>  2 files changed, 23 insertions(+), 3 deletions(-)
> 
> Index: linux/drivers/acpi/bus.c
> ===================================================================
> --- linux.orig/drivers/acpi/bus.c
> +++ linux/drivers/acpi/bus.c
> @@ -257,7 +257,15 @@ static int __acpi_bus_get_power(struct a
>  }
>  
>  
> -static int __acpi_bus_set_power(struct acpi_device *device, int state)
> +/**
> + * acpi_device_set_power - Set power state of an ACPI device.
> + * @device: Device to set the power state of.
> + * @state: New power state to set.
> + *
> + * Callers must ensure that the device is power manageable before using this
> + * function.
> + */
> +int acpi_device_set_power(struct acpi_device *device, int state)
>  {
>  	int result = 0;
>  	acpi_status status = AE_OK;
> @@ -341,6 +349,7 @@ static int __acpi_bus_set_power(struct a
>  
>  	return result;
>  }
> +EXPORT_SYMBOL(acpi_device_set_power);
>  
>  
>  int acpi_bus_set_power(acpi_handle handle, int state)
> @@ -359,7 +368,7 @@ int acpi_bus_set_power(acpi_handle handl
>  		return -ENODEV;
>  	}
>  
> -	return __acpi_bus_set_power(device, state);
> +	return acpi_device_set_power(device, state);
>  }
>  EXPORT_SYMBOL(acpi_bus_set_power);
>  
> @@ -402,7 +411,7 @@ int acpi_bus_update_power(acpi_handle ha
>  	if (result)
>  		return result;
>  
> -	result = __acpi_bus_set_power(device, state);
> +	result = acpi_device_set_power(device, state);
>  	if (!result && state_p)
>  		*state_p = state;
>  
> Index: linux/include/acpi/acpi_bus.h
> ===================================================================
> --- linux.orig/include/acpi/acpi_bus.h
> +++ linux/include/acpi/acpi_bus.h
> @@ -338,6 +338,7 @@ acpi_status acpi_bus_get_status_handle(a
>  				       unsigned long long *sta);
>  int acpi_bus_get_status(struct acpi_device *device);
>  int acpi_bus_set_power(acpi_handle handle, int state);
> +int acpi_device_set_power(struct acpi_device *device, int state);
>  int acpi_bus_update_power(acpi_handle handle, int *state_p);
>  bool acpi_bus_power_manageable(acpi_handle handle);
>  bool acpi_bus_can_wakeup(acpi_handle handle);
> @@ -482,6 +483,16 @@ static inline int acpi_pm_device_sleep_w
>  }
>  #endif
>  
> +static inline bool acpi_device_power_manageable(struct acpi_device *adev)
> +{
> +	return adev->flags.power_manageable;
> +}
> +
> +static inline bool acpi_device_can_wakeup(struct acpi_device *adev)
> +{
> +	return adev->wakeup.flags.valid;
> +}
> +
>  #else	/* CONFIG_ACPI */
>  
>  static inline int register_acpi_bus_type(void *bus) { return 0; }
> 
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