Re: [PATCH 07/13] arm64: dts: ti: k3-am69-aquila: fix USB clocking for compliance

[Francesco Dolcini <francesco@dolcini.it>]

Hi Siddharth,

On Tue, May 05, 2026 at 04:36:08PM +0530, Siddharth Vadapalli wrote:
> 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: 39ac6623b1d8 ("arm64: dts: ti: Add Aquila AM69 Support")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
> ---
>  arch/arm64/boot/dts/ti/k3-am69-aquila.dtsi | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/ti/k3-am69-aquila.dtsi b/arch/arm64/boot/dts/ti/k3-am69-aquila.dtsi
> index 5119baf62a4c..7c98ee81ccb5 100644
> --- a/arch/arm64/boot/dts/ti/k3-am69-aquila.dtsi
> +++ b/arch/arm64/boot/dts/ti/k3-am69-aquila.dtsi
> @@ -1423,6 +1423,7 @@ serdes0_usb0_ss_link: phy@3 {
>  		resets = <&serdes_wiz0 4>;
>  		cdns,num-lanes = <1>;
>  		cdns,phy-type = <PHY_TYPE_USB3>;
> +		cdns,ssc-mode = <2>; /* 2 for internal SSC */
>  	};
>  };
>  
> @@ -1502,6 +1503,11 @@ &serdes_ln_ctrl {
>  
>  &serdes_wiz0 {
>  	status = "okay";
> +	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 */

These properties must go before status. Please see the coding guideline.

Francesco