On Friday, March 30, 2012, Len Brown wrote:
> From: Zhang Rui <rui.zhang@xxxxxxxxx>
>
> If a device has _PR3, it means the device supports D3_COLD.
> Add the ability to validate and enter D3_COLD state in ACPI.
This patch is wrong, IMO.
Namely, _PR3 lists power resources that are supposed to be "on"
in D3, which means that in that state the device is not completely
off, so this must be D3_hot and not D3_cold.
So. _PR3 means D3_hot is supported. D3_cold, on the other hand,
is always supported, although it may not be accessible through any
direct software action (for example, it may be necessary to power
down a bus to put devices on it into D3_cold).
Thanks,
Rafael
> Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
> Signed-off-by: Lin Ming <ming.m.lin@xxxxxxxxx>
> Signed-off-by: Len Brown <len.brown@xxxxxxxxx>
> ---
> 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);
>
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