PCIe ports reserved for VMD use are not visible to BIOS and therefore not
configured to enable PCIe ASPM or LTR values (which BIOS will configure if
they are not set). Lack of this programming results in high power
consumption on laptops as reported in bugzilla. For affected products use
pci_enable_link_state to set the allowed link states for devices on the
root ports. Also set the LTR value to the maximum value needed for the SoC.
This is a workaround for products from Rocket Lake through Alder Lake.
Raptor Lake, the latest product at this time, has already implemented LTR
configuring in BIOS. Future products will move ASPM configuration back to
BIOS as well. As this solution is intended for laptops, support is not
added for hotplug or for devices downstream of a switch on the root port.
Add pci_enable_link_state() to allow devices to change the default BIOS
configured states. Clears the BIOS default settings then sets the new
states and reconfigures the link under the semaphore. Also add
PCIE_LINK_STATE_ALL macro for convenience for callers that want to enable
all link states.
Signed-off-by: Michael Bottini <email address hidden>
Signed-off-by: David E. Box <email address hidden>
Acked-by: Bjorn Helgaas <email address hidden>
(cherry picked from https://<email address hidden>/)
Signed-off-by: You-Sheng Yang (vicamo) <email address hidden>
If the IOMMU is in use and an untrusted device is connected to an external
facing port but the address requested isn't page aligned will cause the
kernel to attempt to use bounce buffers.
If for some reason the bounce buffers have not been allocated this is a
problem that should be made apparent to the user.
Signed-off-by: Mario Limonciello <email address hidden>
(cherry picked from https://lore<email address hidden>)
Signed-off-by: You-Sheng Yang (vicamo) <email address hidden>
