Re: [PATCH v2 02/13] arm64: dts: ti: k3-am642-phyboard-electra-rdk: fix USB clocking for compliance

[Siddharth Vadapalli <s-vadapalli@ti.com>]

On 07/05/26 13:55, Wadim Egorov wrote:
> Hi,
> 
> On 5/6/26 5:09 PM, 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: c48ac0efe6d7 ("arm64: dts: ti: Add support for phyBOARD-Electra-AM642")
>> Cc: <stable@vger.kernel.org>
>> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
>> ---
>>
>> v1:
>> https://lore.kernel.org/r/20260505110631.1144200-3-s-vadapalli@ti.com/
>> No changes since v1.
>>
>>   arch/arm64/boot/dts/ti/k3-am642-phyboard-electra-rdk.dts | 9 +++++++++
>>   1 file changed, 9 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/ti/k3-am642-phyboard-electra-rdk.dts b/arch/arm64/boot/dts/ti/k3-am642-phyboard-electra-rdk.dts
>> index 793538f94942..a85d7d08bd1b 100644
>> --- a/arch/arm64/boot/dts/ti/k3-am642-phyboard-electra-rdk.dts
>> +++ b/arch/arm64/boot/dts/ti/k3-am642-phyboard-electra-rdk.dts
>> @@ -439,12 +439,21 @@ &sdhci1 {
>>   	status = "okay";
>>   };
>>   
>> +&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 */
> 
> I don't think the comments are very helpful. The property names already give a meaning.

The comments have been added for three reasons:
1. The meaning of the following properties isn't obvious:
	ti,core-clk-sel = <1>
	ti,ssc-type = <1>
2. For ease of 'grepping'. Grepping for '33 KHz' for example based on the 
USB 3.2 Specification's modulation rate will not show '33000' in the results.
3. Completeness / Consistency. Since some of the less obvious properties 
have been described via comments, the remaining have also been commented 
on, although it is obvious what it means (ti,ssc-enable for example).

Unless you have a strong objection to removing the comments, I would prefer 
retaining them. Please let me know.

Regards,
Siddharth.