Re: [RFC PATCH v2 1/8] ACPI: Introduce ACPI D3_COLD state support

[Aaron Lu <aaron.lu@amd.com>]

Hi,

On Thu, Mar 01, 2012 at 05:02:50PM +0800, Lin Ming wrote:
> From: Zhang Rui <rui.zhang@intel.com>
> 
> If a device has _PR3, it means the device supports D3_COLD.

This confused me...So this means if a device is put to D3, instead of
turning up the power resources referenced in _PR3, turning them all off
will make the device in D3 cold. This is understandable, but what about
_PR0? What power state this device is in when I turned off all the power
resources referenced in _PR0? Undefined?

I'm also confused with _PS3, what power state the device is in after its
_PS3 is executed? The spec said it will be in D3 cold or D3 hot, so I
guess there is no way to tell, right?

Thanks,
Aaron

> Add the ability to validate and enter D3_COLD state in ACPI.
> 
> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> Signed-off-by: Lin Ming <ming.m.lin@intel.com>
> ---
>  drivers/acpi/power.c |    4 ++--
>  drivers/acpi/scan.c  |    7 +++++++
>  2 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c
> index 9ac2a9f..0d681fb 100644
> --- a/drivers/acpi/power.c
> +++ b/drivers/acpi/power.c
> @@ -500,14 +500,14 @@ int acpi_power_transition(struct acpi_device *device, int state)
>  {
>  	int result;
>  
> -	if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
> +	if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3_COLD))
>  		return -EINVAL;
>  
>  	if (device->power.state == state)
>  		return 0;
>  
>  	if ((device->power.state < ACPI_STATE_D0)
> -	    || (device->power.state > ACPI_STATE_D3))
> +	    || (device->power.state > ACPI_STATE_D3_COLD))
>  		return -ENODEV;
>  
>  	/* TBD: Resources must be ordered. */
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 8ab80ba..571396c 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -885,6 +885,13 @@ static int acpi_bus_get_power_flags(struct acpi_device *device)
>  				acpi_bus_add_power_resource(ps->resources.handles[j]);
>  		}
>  
> +		/* The exist of _PR3 indicates D3Cold support */
> +		if (i == ACPI_STATE_D3) {
> +			status = acpi_get_handle(device->handle, object_name, &handle);
> +			if (ACPI_SUCCESS(status))
> +				device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1;
> +		}
> +
>  		/* Evaluate "_PSx" to see if we can do explicit sets */
>  		object_name[2] = 'S';
>  		status = acpi_get_handle(device->handle, object_name, &handle);
> -- 
> 1.7.2.5
> 
>