[PATCH v2 04/13] arm64: dts: ti: k3-am642-tqma64xxl: fix USB clocking for compliance

[Siddharth Vadapalli <s-vadapalli@ti.com>]

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: 4717a36f31ec ("arm64: dts: ti: Add TQ-Systems TQMa64XxL SoM and MBaX4XxL carrier board Device Trees")
Cc: <stable@vger.kernel.org>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
---

v1:
https://lore.kernel.org/r/20260505110631.1144200-5-s-vadapalli@ti.com/
No changes since v1.

 arch/arm64/boot/dts/ti/k3-am642-tqma64xxl-mbax4xxl.dts | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-am642-tqma64xxl-mbax4xxl.dts b/arch/arm64/boot/dts/ti/k3-am642-tqma64xxl-mbax4xxl.dts
index 46be6824dd16..e5d1b2ebf2c8 100644
--- a/arch/arm64/boot/dts/ti/k3-am642-tqma64xxl-mbax4xxl.dts
+++ b/arch/arm64/boot/dts/ti/k3-am642-tqma64xxl-mbax4xxl.dts
@@ -504,6 +504,14 @@ &serdes_refclk {
 	bootph-all;
 };
 
+&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_usb_link: phy@0 {
 		reg = <0>;
@@ -512,6 +520,7 @@ serdes0_usb_link: phy@0 {
 		bootph-all;
 		cdns,num-lanes = <1>;
 		cdns,phy-type = <PHY_TYPE_USB3>;
+		cdns,ssc-mode = <2>; /* 2 for internal SSC */
 	};
 };
 
-- 
2.51.1