@@ -2176,7 +2176,7 @@ void pci_config_pm_runtime_put(struct pci_dev *pdev)
* @bridge: Bridge to check
*
* This function checks if it is possible to move the bridge to D3.
- * Currently we only allow D3 for recent enough PCIe ports.
+ * Currently we only allow D3 for recent enough PCIe ports and Thunderbolt.
*/
static bool pci_bridge_d3_possible(struct pci_dev *bridge)
{
@@ -2202,6 +2202,9 @@ static bool pci_bridge_d3_possible(struct pci_dev *bridge)
year >= 2015) {
return true;
}
+ /* Even the oldest 2010 Thunderbolt controller supports D3. */
+ if (bridge->is_thunderbolt)
+ return true;
break;
}
Currently PCIe ports are only allowed to go to D3 if the BIOS is dated 2015 or newer to avoid potential issues with old chipsets. However for Thunderbolt we know that even the oldest controller, Light Ridge (2010), is able to suspend its ports to D3 just fine. We're about to add runtime PM for Thunderbolt on the Mac. Apple has released two EFI security updates in 2015 which encompass all machines with Thunderbolt, but the achieved power saving should be made available to users even if they haven't updated their BIOS. To this end, special-case Thunderbolt in pci_bridge_d3_possible(). This allows the Thunderbolt controller to power down but the root port to which the Thunderbolt controller is attached remains in D0 unless the EFI update is installed. Users can pass pcie_port_pm=force on the kernel command line if they cannot install the EFI update but still want to benefit from the additional power saving of putting the root port to D3. In practice root ports can be suspended to D3 without problems at least on 2012 Ivy Bridge machines. If the BIOS cut-off date is ever lowered to 2010, the Thunderbolt special case can be removed. Signed-off-by: Lukas Wunner <lukas@wunner.de> --- drivers/pci/pci.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)