[PATCH] Use maximum latency when determining L1 ASPM

[Ian Kumlien <ian.kumlien@gmail.com>]

The current solution verifies per "hop" but doesn't
check the maximum latency, instead it checks the
current "hops" max latency for upstream and downstrea,

This would work if all "hops" have the same latency, but:

root -> a -> b -> c -> endpoint

If c or b has the higest latency, it might not register

Fix this by maintaining a maximum value for comparison

Signed-off-by: Ian Kumlien <ian.kumlien@gmail.com>
---
 drivers/pci/pcie/aspm.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index b17e5ffd31b1..bd53fba7f382 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -434,7 +434,7 @@ static void pcie_get_aspm_reg(struct pci_dev *pdev,
 
 static void pcie_aspm_check_latency(struct pci_dev *endpoint)
 {
-	u32 latency, l1_switch_latency = 0;
+	u32 latency, l1_max_latency = 0, l1_switch_latency = 0;
 	struct aspm_latency *acceptable;
 	struct pcie_link_state *link;
 
@@ -470,8 +470,9 @@ static void pcie_aspm_check_latency(struct pci_dev *endpoint)
 		 * substate latencies (and hence do not do any check).
 		 */
 		latency = max_t(u32, link->latency_up.l1, link->latency_dw.l1);
+		l1_max_latency = max_t(u32, latency, l1_max_latency);
 		if ((link->aspm_capable & ASPM_STATE_L1) &&
-		    (latency + l1_switch_latency > acceptable->l1))
+		    (l1_max_latency + l1_switch_latency > acceptable->l1))
 			link->aspm_capable &= ~ASPM_STATE_L1;
 		l1_switch_latency += 1000;
 
-- 
2.27.0