[PATCH 13/13] arm64: dts: ti: k3-j784s4-j742s2-evm-common: 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: 39b623c05c46 ("arm64: dts: ti: Refactor J784s4-evm to a common file")
Fixes: bed97e94ee2d ("arm64: dts: ti: k3-j784s4-evm: Enable USB3 support")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@xxxxxx>
---
 arch/arm64/boot/dts/ti/k3-j784s4-j742s2-evm-common.dtsi | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-j784s4-j742s2-evm-common.dtsi b/arch/arm64/boot/dts/ti/k3-j784s4-j742s2-evm-common.dtsi
index ff3a85cbc524..0884773ad230 100644
--- a/arch/arm64/boot/dts/ti/k3-j784s4-j742s2-evm-common.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-j784s4-j742s2-evm-common.dtsi
@@ -1010,12 +1010,18 @@ serdes0_usb_link: phy@3 {
 		cdns,num-lanes = <1>;
 		#phy-cells = <0>;
 		cdns,phy-type = <PHY_TYPE_USB3>;
+		cdns,ssc-mode = <2>; /* 2 for internal SSC */
 		resets = <&serdes_wiz0 4>;
 	};
 };
 
 &serdes_wiz0 {
 	status = "okay";
+	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 */
 };
 
 &usb_serdes_mux {
-- 
2.51.1