Program ASPM on PCIe root ports when no endpoint device is connected
at boot. This ensures proper power management for TBT ports that often
do not have devices connected at boot.
Add pciexp_enable_aspm_root_port_only() to program ASPM based on the
root port's Link Capabilities, and call it from pciexp_scan_bus() when
no children are detected on a root port.
TEST=build/boot Starlabs Starfighter MTL, verify ASPM enabled on TBT
ports even when no devices attached via lspci:
LnkCtrl: ASPM L1 Enabled
Change-Id: I1da6d36afcbe18411c01ceabf8b903c4ae13cd73
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/90913
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sean Rhodes <sean@starlabs.systems>
a2a868f199