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ACPI/PM: specify lowest allowed state for device sleep state

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Lower device sleep state can save more power, but has more exit
latency too.  Sometimes, to satisfy some power QoS and other
requirement, we need to constrain the lowest device sleep state.

In this patch, a parameter to specify lowest allowed state for
acpi_pm_device_sleep_state is added.  So that the caller can enforce
the constraint via the parameter.

This is needed by PCIe D3cold support, where the lowest power state
allowed may be D3_HOT instead of default D3_COLD.

CC: Len Brown <lenb@kernel.org>
CC: linux-acpi@vger.kernel.org
Reviewed-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Huang Ying
2012-06-23 10:23:48 +08:00
committed by Bjorn Helgaas
parent cfaf025112
commit ee85f54371
4 changed files with 26 additions and 11 deletions
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3
drivers/pci/pci-acpi.c
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@@ -189,7 +189,8 @@ static pci_power_t acpi_pci_choose_state(struct pci_dev *pdev)
{
int acpi_state;
acpi_state = acpi_pm_device_sleep_state(&pdev->dev, NULL);
acpi_state = acpi_pm_device_sleep_state(&pdev->dev, NULL,
ACPI_STATE_D3);
if (acpi_state < 0)
return PCI_POWER_ERROR;