From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vidya Sagar Subject: [PATCH V12 08/12] dt-bindings: Add PCIe supports-clkreq property Date: Mon, 1 Jul 2019 18:10:06 +0530 Message-ID: <20190701124010.7484-9-vidyas@nvidia.com> References: <20190701124010.7484-1-vidyas@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <20190701124010.7484-1-vidyas@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: lorenzo.pieralisi@arm.com, bhelgaas@google.com, robh+dt@kernel.org, mark.rutland@arm.com, thierry.reding@gmail.com, jonathanh@nvidia.com, kishon@ti.com, catalin.marinas@arm.com, will.deacon@arm.com, jingoohan1@gmail.com, gustavo.pimentel@synopsys.com Cc: digetx@gmail.com, mperttunen@nvidia.com, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kthota@nvidia.com, mmaddireddy@nvidia.com, vidyas@nvidia.com, sagar.tv@gmail.com List-Id: devicetree@vger.kernel.org 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 sub states might lead to downstream devices falling off 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 Reviewed-by: Rob Herring Reviewed-by: Thierry Reding --- Changes since [v11]: * Rebased on top of linux-next top of the tree Changes since [v10]: * None Changes since [v9]: * None Changes since [v8]: * None Changes since [v7]: * None Changes since [v6]: * None Changes since [v5]: * s/Documentation\/devicetree/dt-bindings/ in the subject Changes since [v4]: * None Changes since [v3]: * Rebased on top of linux-next top of the tree Changes since [v2]: * None Changes since [v1]: * This is a new patch in v2 series Documentation/devicetree/bindings/pci/pci.txt | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt index 2a5d91024059..29bcbd88f457 100644 --- a/Documentation/devicetree/bindings/pci/pci.txt +++ b/Documentation/devicetree/bindings/pci/pci.txt @@ -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 ------------------------- -- 2.17.1