arm64: dts: imx8qm-mek: Add supports-clkreq property to PCIe M.2 port

According to PCIe r6.1, sec 5.5.1.

The following rules define how the L1.1 and L1.2 substates are entered:
Both the Upstream and Downstream Ports must monitor the logical state of
the CLKREQ# signal.

Typical implement is using open drain, which connect RC's clkreq# to
EP's clkreq# together and pull up clkreq#.

imx8qm-mek matches this requirement, so add supports-clkreq to allow
PCIe device enter ASPM L1 Sub-State.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

diff --git a/arch/arm64/boot/dts/freescale/imx8qm-mek.dts b/arch/arm64/boot/dts/freescale/imx8qm-mek.dts
index 6a75ec612684e1e8e36346cdfdcc3d8ef490ace3..0bf2ee33618e862e7e6547bea2020c9aec1fea31 100644 (file)
--- a/arch/arm64/boot/dts/freescale/imx8qm-mek.dts
+++ b/arch/arm64/boot/dts/freescale/imx8qm-mek.dts
@@ -784,6 +784,7 @@
        pinctrl-names = "default";
        reset-gpio = <&lsio_gpio4 29 GPIO_ACTIVE_LOW>;
        vpcie-supply = <&reg_pciea>;
+       supports-clkreq;
        status = "okay";
 };