@@ -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.
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. Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> --- Changes in v6: None Changes in v5: None Changes in v4: None Changes in v3: None Changes in v2: None Documentation/devicetree/bindings/pci/pci.txt | 6 ++++++ 1 file changed, 6 insertions(+)