[PATCH 02/13] arm64: dts: ti: k3-am642-phyboard-electra-rdk: fix USB clocking for compliance

[Siddharth Vadapalli]

According to section "6.5.3 Normative Spread Spectrum Clocking (SSC)" of
the USB 3.2 Specification, SSC should be enabled by default. This protects
against EMI violations. Hence, enable internal SSC for USB SuperSpeed.

Fixes: c48ac0efe6d7 ("arm64: dts: ti: Add support for phyBOARD-Electra-AM642")
Cc: <stable at vger.kernel.org>
Signed-off-by: Siddharth Vadapalli <s-vadapalli at ti.com>
---
 arch/arm64/boot/dts/ti/k3-am642-phyboard-electra-rdk.dts | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-am642-phyboard-electra-rdk.dts b/arch/arm64/boot/dts/ti/k3-am642-phyboard-electra-rdk.dts
index 793538f94942..a85d7d08bd1b 100644
--- a/arch/arm64/boot/dts/ti/k3-am642-phyboard-electra-rdk.dts
+++ b/arch/arm64/boot/dts/ti/k3-am642-phyboard-electra-rdk.dts
@@ -439,12 +439,21 @@ &sdhci1 {
 	status = "okay";
 };
 
+&serdes_wiz0 {
+	ti,core-clk-sel = <1>;  /* Select internal reference clock */
+	ti,ssc-enable; /* Enable SSC */
+	ti,ssc-type = <1>; /* 1 for Downspread */
+	ti,ssc-frequency-hz = <33000>; /* 33 KHz */
+	ti,ssc-depth-per-mil = <5>; /* 0.5% depth */
+};
+
 &serdes0 {
 	serdes0_pcie_usb_link: phy at 0 {
 		reg = <0>;
 		cdns,num-lanes = <1>;
 		#phy-cells = <0>;
 		cdns,phy-type = <PHY_TYPE_USB3>;
+		cdns,ssc-mode = <2>; /* 2 for internal SSC */
 		resets = <&serdes_wiz0 1>;
 	};
 };
-- 
2.51.1