Commit 7b31a72e authored Aug 13, 2019 by Vidya Sagar Committed by Lorenzo Pieralisi Aug 13, 2019

dt-bindings: Add PCIe supports-clkreq property



Some host controllers need to know the existence of clkreq signal routing
to downstream devices to be able to advertise low power features like
ASPM L1 substates. Without clkreq signal routing being present, enabling
ASPM L1 substates might lead to downstream devices being disconnected
from the bus. Hence a new device tree property 'supports-clkreq' is added
to make such host controllers aware of clkreq signal routing to
downstream devices.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Thierry Reding <treding@nvidia.com>

parent 07f123de

Documentation/devicetree/bindings/pci/pci.txt

+5 −0

Original line number	Diff line number	Diff line
		@@ -27,6 +27,11 @@ driver implementation may support the following properties:
		- reset-gpios:
		If present this property specifies PERST# GPIO. Host drivers can parse the
		GPIO and apply fundamental reset to endpoints.
		- supports-clkreq:
		If present this property specifies that CLKREQ signal routing exists from
		root port to downstream device and host bridge drivers can do programming
		which depends on CLKREQ signal existence. For example, programming root port
		not to advertise ASPM L1 Sub-States support if there is no CLKREQ signal.

		PCI-PCI Bridge properties
		-------------------------

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