mb/prodrive/hermes: Enable LTR for all PCIe ports

Set the `PcieRpLtrEnable` option to enable the LTR capability on all PCH
PCIe root ports.

TEST=Verify LTR capability enabled in `DevCap2` using `lspci -vv`

Change-Id: I07ea37d178ea61d904c4f131fdea31479e899ef3
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58326
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/mainboard/prodrive/hermes/devicetree.cb b/src/mainboard/prodrive/hermes/devicetree.cb
index a57931ba94..8faf016e7c 100644
--- a/src/mainboard/prodrive/hermes/devicetree.cb
+++ b/src/mainboard/prodrive/hermes/devicetree.cb
@@ -198,34 +198,42 @@ chip soc/intel/cannonlake
 		end
 		device pci 1c.4 on	# PCIe root port 5 (PHY 3)
 			register "PcieRpEnable[4]" = "1"
+			register "PcieRpLtrEnable[4]" = "1"
 		end
 		device pci 1c.5 on	# PCIe root port 6 (PHY 4)
 			register "PcieRpEnable[5]" = "1"
+			register "PcieRpLtrEnable[5]" = "1"
 		end
 		device pci 1c.6 on	# PCIe root port 7 (PHY 2)
 			register "PcieRpEnable[6]" = "1"
+			register "PcieRpLtrEnable[6]" = "1"
 		end
 		device pci 1c.7 on	# PCIe root port 8 (PHY 1)
 			register "PcieRpEnable[7]" = "1"
+			register "PcieRpLtrEnable[7]" = "1"
 		end
 		device pci 1d.0 on	# PCIe root port 9 (M2 M)
 			smbios_slot_desc "SlotTypePciExpressGen3X16" "SlotLengthOther" "M2 M" "SlotDataBusWidth4X"
 			register "PcieRpEnable[8]" = "1"
+			register "PcieRpLtrEnable[8]" = "1"
 			register "PcieRpSlotImplemented[8]" = "1"
 		end
 		device pci 1d.5 on	# PCIe root port 14 (PHY 0)
 			register "PcieRpEnable[13]" = "1"
+			register "PcieRpLtrEnable[13]" = "1"
 		end
 		device pci 1d.6 on	# PCIe root port 15 (BMC)
 			device pci 00.0 on	# Aspeed PCI Bridge
 				device pci 00.0 on end  # Aspeed 2500 VGA
 			end
 			register "PcieRpEnable[14]" = "1"
+			register "PcieRpLtrEnable[14]" = "1"
 			register "PcieRpSlotImplemented[14]" = "1"
 		end
 		device pci 1d.7 on	# PCIe root port 16 (M.2 E/CNVi)
 			# Disabled when CNVi is present
 			register "PcieRpEnable[15]" = "1"
+			register "PcieRpLtrEnable[15]" = "1"
 			register "PcieRpSlotImplemented[15]" = "1"
 		end
 		device pci 1e.0 on  end # UART #0