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SubjectRe: [RFC PATCH 1/6] ACPI: Introduce ACPI D3_COLD state support
Date
On Monday, February 13, 2012, Lin Ming wrote:
> From: Zhang Rui <rui.zhang@intel.com>
>
> If a device has _PR3._ON, it means the device supports D3_HOT.
> If a device has _PR3._OFF, it means the device supports D3_COLD.
> Add the ability to validate and enter D3_COLD state in ACPI.
>
> Signed-off-by: Zhang Rui <rui.zhang@intel.com>

This is supposed to be ACPI 5.0 support, right?

So can anyone please tell me what part of the ACPI 5.0 spec is the
basis of this patch, because I can't see that immediately?

The only places where D3Cold is _mentioned_ are Section 7.2.12 (_PRE, which
appears to be new in 5.0), Section 7.2.20 (_S0W), Section 7.2.21 (_S1W),
Section 7.2.22 (_S2W), Section 7.2.23 (_S3W) and Section 7.2.24 (_S4W).
None of them mentions those _PR3._ON and _PR3._OFF things above.

Moreover, my understanding of the spec is that D3Cold means all of the
power resources returned by _PR3 are "off" (whereas some of them will be
"on" in D3hot).

> ---
> drivers/acpi/power.c | 4 ++--
> drivers/acpi/scan.c | 10 +++++++++-
> 2 files changed, 11 insertions(+), 3 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..a9d4391 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -881,8 +881,16 @@ static int acpi_bus_get_power_flags(struct acpi_device *device)
>
> device->power.flags.power_resources = 1;
> ps->flags.valid = 1;
> - for (j = 0; j < ps->resources.count; j++)
> + for (j = 0; j < ps->resources.count; j++) {
> acpi_bus_add_power_resource(ps->resources.handles[j]);
> + /* Check for D3_COLD support. _PR3._OFF equals D3_COLD ? */
> + if (i == ACPI_STATE_D3) {
> + if (j == 0)
> + device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1;
> + status = acpi_get_handle(ps->resources.handles[j], "_OFF", &handle);
> + device->power.states[ACPI_STATE_D3_COLD].flags.valid &= ACPI_SUCCESS(status);
> + }
> + }

Sorry, but this doesn't make sense to me. Power resources always have
the _OFF method, right?

> }
>
> /* Evaluate "_PSx" to see if we can do explicit sets */
>

Rafael


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