[PATCH v2 05/13] arm64: dts: ti: k3-am68-phyboard-izar: 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: 8bc3b1c86452 ("arm64: dts: ti: Add basic support for phyBOARD-Izar-AM68x")
Cc: <stable at vger.kernel.org>
Signed-off-by: Siddharth Vadapalli <s-vadapalli at ti.com>
---

v1:
https://lore.kernel.org/r/20260505110631.1144200-6-s-vadapalli@ti.com/
No changes since v1.

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

diff --git a/arch/arm64/boot/dts/ti/k3-am68-phyboard-izar.dts b/arch/arm64/boot/dts/ti/k3-am68-phyboard-izar.dts
index 225fe7a7803b..d9b61e426ff8 100644
--- a/arch/arm64/boot/dts/ti/k3-am68-phyboard-izar.dts
+++ b/arch/arm64/boot/dts/ti/k3-am68-phyboard-izar.dts
@@ -505,6 +505,14 @@ &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";
 
@@ -522,6 +530,7 @@ serdes0_usb_link: phy at 1 {
 		#phy-cells = <0>;
 		resets = <&serdes_wiz0 2>;
 		cdns,phy-type = <PHY_TYPE_USB3>;
+		cdns,ssc-mode = <2>; /* 2 for internal SSC */
 	};
 };
 
-- 
2.51.1