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authorRafael J. Wysocki2019-06-25 14:06:13 +0200
committerRafael J. Wysocki2019-06-27 12:30:00 +0200
commitf850a48a07996bfd7bd1b2e52f57b5ee55125482 (patch)
treefc9bac44a5c925595f84591b675b103519946567 /net/rxrpc
parent21ba237926227121dacccaf5d7863b0cb50f3eda (diff)
ACPI: PM: Allow transitions to D0 to occur in special cases
If a device with ACPI PM is left in D0 during a system-wide transition to the S3 (suspend-to-RAM) or S4 (hibernation) sleep state, the actual state of the device need not be D0 during resume from it, although its power.state value will still reflect D0 (that is, the power state from before the system-wide transition). In that case, the acpi_device_set_power() call made to ensure that the power state of the device will be D0 going forward has no effect, because the new state (D0) is equal to the one reflected by the device's power.state value. That does not affect power resources, which are taken care of by acpi_resume_power_resources() called from acpi_pm_finish() during resume from system-wide sleep states, but it still may be necessary to invoke _PS0 for the device on top of that in order to finalize its transition to D0. For this reason, modify acpi_device_set_power() to allow transitions to D0 to occur even if D0 is the current power state of the device according to its power.state value. That will not affect power resources, which are assumed to be in the right configuration already (as reflected by the current values of their reference counters), but it may cause _PS0 to be evaluated for the device. However, evaluating _PS0 for a device already in D0 may lead to confusion in general, so invoke _PSC (if present) to check the device's current power state upfront and only evaluate _PS0 for it if _PSC has returned a power state different from D0. [If _PSC is not present or the evaluation of it fails, the power state of the device is assumed to be D0 at this point.] Fixes: 20dacb71ad28 (ACPI / PM: Rework device power management to follow ACPI 6) Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
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