From 2928d69ec4afb9d37f0d34ef335dd8c89a7d5df6 Mon Sep 17 00:00:00 2001 From: Shawn Lin Date: Tue, 18 Oct 2016 09:45:08 +0800 Subject: [PATCH] UPSTREAM: Documentation/devicetree: Add new property to specify the max link speed Some of the host drivers have the requirement of knowing whether the EP would never train at some link speed at all. For instance, on some boards, the link won't train at 5 GT/s but the host driver still sacrifice some cycle to wait for the resule of training at 5 GT/s as the host could actually support 5 GT/s. So we could parse this new property and make the host drivers be aware of these cases. Change-Id: I7f557282462a7146d8d15af560001c81ccc7e1a7 Signed-off-by: Shawn Lin Signed-off-by: Bjorn Helgaas Acked-by: Rob Herring Signed-off-by: Shawn Lin (am from git.kernel.org/cgit/linux/kernel/git/next/linux-next.git commit 2fa39159b6a9931d6fd82ecbe65357e0ad77e1a4) --- Documentation/devicetree/bindings/pci/pci.txt | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt index 08dcfad09f8d..e7d97a3bd17f 100644 --- a/Documentation/devicetree/bindings/pci/pci.txt +++ b/Documentation/devicetree/bindings/pci/pci.txt @@ -18,3 +18,9 @@ driver implementation may support the following properties: host bridges in the system, otherwise potentially conflicting domain numbers may be assigned to root buses behind different host bridges. The domain number for each host bridge in the system must be unique. +- max-link-speed: + If present this property specifies PCI gen for link capability. The host drivers + could add this as a strategy to avoid unnecessary operation for unsupported + link speed, for instance, trying to do training for unsupported link speed, etc. + Must be '4' for gen4, '3' for gen3, '2' for gen2, and '1' for gen1. Any other + values are invalid. -- 2.34.1