Re: [PATCH net-next v3 1/2] dpll: add fractional frequency offset to pin-parent-device

[Jiri Pirko <jiri@resnulli.us>]

Thu, May 07, 2026 at 03:33:42AM +0200, kuba@kernel.org wrote:
>On Mon,  4 May 2026 17:53:39 +0200 Ivan Vecera wrote:
>> +          At top level this represents the RX vs TX symbol rate
>> +          offset on the media associated with the pin.
>
>Isn't this a hacky hack? I'd think that pin is in or out.
>Having a freq offset between two pins or pin and parent's
>ref lock makes sense. This new interpretation sounds like
>we are trying to shove a difference between two pins into one?

The pin is in, but it is associated with SyncE port that has RX/TX
symbol rate offset. As the doc says, the "offset on the media associated
with the pin". Why is that hack?


>
>> @@ -299,6 +299,10 @@ zl3073x_dpll_input_pin_ffo_get(const struct dpll_pin *dpll_pin, void *pin_priv,
>>  {
>>  	struct zl3073x_dpll_pin *pin = pin_priv;
>>  
>> +	/* Only rx vs tx symbol rate FFO is supported */
>> +	if (dpll)
>> +		return -ENODATA;
>> +
>>  	*ffo = pin->freq_offset;
>
>It's easy for driver authors to forget this sort of validation.
>We should fail close, so it's better to have some "capability"
>bits or something for the driver to opt into getting given format 
>of the call.