[PATCH v2 11/13] arm64: dts: ti: k3-j721e-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: 1bfda92a3a36 ("arm64: dts: ti: Add support for J721E SK")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@xxxxxx>
---

v1:
https://lore.kernel.org/r/20260505110631.1144200-12-s-vadapalli@xxxxxx/
No changes since v1.

 arch/arm64/boot/dts/ti/k3-j721e-sk.dts | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-j721e-sk.dts b/arch/arm64/boot/dts/ti/k3-j721e-sk.dts
index 689ba2ff81f7..79927a34edff 100644
--- a/arch/arm64/boot/dts/ti/k3-j721e-sk.dts
+++ b/arch/arm64/boot/dts/ti/k3-j721e-sk.dts
@@ -960,6 +960,11 @@ &serdes_ln_ctrl {
 &serdes_wiz3 {
 	typec-dir-gpios = <&main_gpio1 3 GPIO_ACTIVE_HIGH>;
 	typec-dir-debounce-ms = <700>;	/* TUSB321, tCCB_DEFAULT 133 ms */
+	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 */
 };
 
 &serdes3 {
@@ -968,6 +973,7 @@ serdes3_usb_link: phy@0 {
 		cdns,num-lanes = <2>;
 		#phy-cells = <0>;
 		cdns,phy-type = <PHY_TYPE_USB3>;
+		cdns,ssc-mode = <2>; /* 2 for internal SSC */
 		resets = <&serdes_wiz3 1>, <&serdes_wiz3 2>;
 		bootph-all;
 	};
@@ -1006,12 +1012,21 @@ &usb0 {
 	bootph-all;
 };
 
+&serdes_wiz2 {
+	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 */
+};
+
 &serdes2 {
 	serdes2_usb_link: phy@1 {
 		reg = <1>;
 		cdns,num-lanes = <1>;
 		#phy-cells = <0>;
 		cdns,phy-type = <PHY_TYPE_USB3>;
+		cdns,ssc-mode = <2>; /* 2 for internal SSC */
 		resets = <&serdes_wiz2 2>;
 	};
 };
-- 
2.51.1