Broadwell: Revise programming flow for write-once registers

Extended PCIe Capability and Advanced Error Report locates at
offset 0x100 is W/O, and the subsequent write following the 1st
write to the register takes no effect.

Signed-off-by: Stefan Reinauer <reinauer@chromium.org>
Original-Commit-Id: d2862b6c1ccc77845cb3e08688a72c0655ea79c9
Original-BUG=chrome-os-partner:31424.
Original-TEST=Build a image and check the programming value is correct on
Original-Samus.
Original-Signed-off-by: Kenji Chen <kenji.chen@intel.com>
Original-Change-Id: I0bed30f516ee0307b4a86cad2f669a18ff4994db
Original-Reviewed-on: https://chromium-review.googlesource.com/219985
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

Change-Id: I3711aa0f1f918baebb4fd77a3615bdf5956ba844
Reviewed-on: http://review.coreboot.org/9209
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/src/soc/intel/broadwell/pcie.c b/src/soc/intel/broadwell/pcie.c
index de23f3e..22eaab9 100644
--- a/src/soc/intel/broadwell/pcie.c
+++ b/src/soc/intel/broadwell/pcie.c
@@ -547,16 +547,15 @@
 
 	pcie_update_cfg8(dev, 0xf5, 0x0f, 0);
 
+	/* Set Extended Capability to offset 200h and Advanced Error Report. */
+	pcie_update_cfg(dev, 0x100, ~(1 << 29) & ~0xfffff, (1 << 29) | 0x10001);
+
 	if (rp == 1 || rp == 5 || rp == 6)
 		pcie_update_cfg8(dev, 0xf7, ~0xc, 0);
 
 	/* Set EOI forwarding disable. */
 	pcie_update_cfg(dev, 0xd4, ~0, (1 << 1));
 
-	/* Set something involving advanced error reporting. */
-	pcie_update_cfg(dev, 0x100, ~((1 << 20) - 1), 0x10001);
-	pcie_update_cfg(dev, 0x100, ~0, (1 << 29));
-
 	/* Read and write back write-once capability registers. */
 	pcie_update_cfg(dev, 0x34, ~0, 0);
 	pcie_update_cfg(dev, 0x40, ~0, 0);