[PATCH v2 08/13] arm64: dts: ti: k3-am69-sk: 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: ff7b5e93f16a ("arm64: dts: ti: k3-am69-sk: Add USB SuperSpeed support")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@xxxxxx>
---

v1:
https://lore.kernel.org/r/20260505110631.1144200-9-s-vadapalli@xxxxxx/
Changes since v1:
- Reordered properties in serdes_wiz0 node to place status at the end.

 arch/arm64/boot/dts/ti/k3-am69-sk.dts | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-am69-sk.dts b/arch/arm64/boot/dts/ti/k3-am69-sk.dts
index e56772a334c5..afd809104d1b 100644
--- a/arch/arm64/boot/dts/ti/k3-am69-sk.dts
+++ b/arch/arm64/boot/dts/ti/k3-am69-sk.dts
@@ -970,6 +970,11 @@ &serdes_ln_ctrl {
 };
 
 &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 */
 	status = "okay";
 };
 
@@ -997,6 +1002,7 @@ 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>;
 	};
 };
-- 
2.51.1