[PATCH v2 12/13] arm64: dts: ti: k3-j722s-evm: fix USB clocking for compliance

Siddharth Vadapalli
2026-05-06T14:10:06Z

From: Luis Parga <luis.parga@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: 485705df5d5f ("arm64: dts: ti: k3-j722s: Enable PCIe and USB support on J722S-EVM")
Cc: <stable@vger.kernel.org>
Signed-off-by: Luis Parga <luis.parga@ti.com>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
---

v1:
https://lore.kernel.org/r/20260505110631.1144200-13-s-vadapalli@ti.com/
Changes since v1:
- Reordered properties in serdes_wiz0 node to place status at the end.

arch/arm64/boot/dts/ti/k3-j722s-evm.dts | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-j722s-evm.dts b/arch/arm64/boot/dts/ti/k3-j722s-evm.dts
index e66330c71593..06b83e94da67 100644
--- a/arch/arm64/boot/dts/ti/k3-j722s-evm.dts
+++ b/arch/arm64/boot/dts/ti/k3-j722s-evm.dts
@@ -745,6 +745,11 @@ &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";
};

@@ -754,6 +759,7 @@ serdes0_usb_link: phy@0 {
cdns,num-lanes = <1>;
#phy-cells = <0>;
cdns,phy-type = <PHY_TYPE_USB3>;
+ cdns,ssc-mode = <2>; /* 2 for internal SSC */
resets = <&serdes_wiz0 1>;
};
};
--
2.51.1