[PATCH v2 06/13] arm64: dts: ti: k3-am68-sk-baseboard: 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: 067878e6cd25 ("arm64: dts: ti: k3-am68-sk: Add DT node for USB")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@xxxxxx>
---

v1:
https://lore.kernel.org/r/20260505110631.1144200-7-s-vadapalli@xxxxxx/
No changes since v1.

 arch/arm64/boot/dts/ti/k3-am68-sk-base-board.dts | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-am68-sk-base-board.dts b/arch/arm64/boot/dts/ti/k3-am68-sk-base-board.dts
index 8178333fb2b4..d44c3685503c 100644
--- a/arch/arm64/boot/dts/ti/k3-am68-sk-base-board.dts
+++ b/arch/arm64/boot/dts/ti/k3-am68-sk-base-board.dts
@@ -793,6 +793,14 @@ &serdes_refclk {
 	clock-frequency = <100000000>;
 };
 
+&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 {
 	status = "okay";
 
@@ -810,6 +818,7 @@ serdes0_usb_link: phy@2 {
 		cdns,num-lanes = <1>;
 		#phy-cells = <0>;
 		cdns,phy-type = <PHY_TYPE_USB3>;
+		cdns,ssc-mode = <2>; /* 2 for internal SSC */
 		resets = <&serdes_wiz0 3>;
 	};
 };
-- 
2.51.1