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

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>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 61e2fefeedab..a9efebc586b4 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -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;