From 94ac327e043ee40d7fc57b54541da50507ef4e99 Mon Sep 17 00:00:00 2001
From: Bjorn Helgaas <bhelgaas@google.com>
Date: Mon, 13 Nov 2017 08:50:30 -0600
Subject: [PATCH] PCI/ASPM: Account for downstream device's Port Common_Mode_Restore_Time
Git-commit: 94ac327e043ee40d7fc57b54541da50507ef4e99
Patch-mainline: v4.15-rc1
References: bsc#1051510

Every Port that supports the L1.2 substate advertises its Port
Common_Mode_Restore_Time, i.e., the time the Port requires to re-establish
common mode when exiting L1.2 (see PCIe r3.1, sec 7.33.2).

Per sec 5.5.3.3.1, when exiting L1.2, the Downstream Port (the device at
the upstream end of the link) must send TS1 training sequences for at least
T(COMMONMODE) after it detects electrical idle exit on the Link.  We want
this to be long enough for both ends of the Link, so we should set it to
the maximum of the Port Common_Mode_Restore_Time for the upstream and
downstream components on the Link.

Previously we only looked at the Port Common_Mode_Restore_Time of the
upstream device, so if the downstream device required more time, we didn't
program the upstream device's T(COMMONMODE) correctly.

Fixes: f1f0366dd6be ("PCI/ASPM: Calculate and save the L1.2 timing parameters")
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Vidya Sagar <vidyas@nvidia.com>
Acked-by: Rajat Jain <rajatja@google.com>
Cc: stable@vger.kernel.org	# v4.11+
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/pci/pcie/aspm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -452,7 +452,7 @@ static void aspm_calc_l1ss_info(struct p
 
 	/* Choose the greater of the two T_cmn_mode_rstr_time */
 	val1 = (upreg->l1ss_cap >> 8) & 0xFF;
-	val2 = (upreg->l1ss_cap >> 8) & 0xFF;
+	val2 = (dwreg->l1ss_cap >> 8) & 0xFF;
 	if (val1 > val2)
 		link->l1ss.ctl1 |= val1 << 8;
 	else