Re: [PATCH net-next v5 1/4] dpll: add DPLL_PIN_TYPE_INT_NCO pin type
From: Ivan Vecera
Date: Mon Jun 08 2026 - 13:04:35 EST
On 6/8/26 1:33 PM, Vadim Fedorenko wrote:
On 04/06/2026 17:42, Ivan Vecera wrote:
On 6/4/26 5:16 PM, Jakub Kicinski wrote:
On Thu, 4 Jun 2026 17:01:36 +0200 Ivan Vecera wrote:
Purely going on intuition here but feels like NCO should be a mode
(enum dpll_mode) rather than one of the input pins?
More acks here would be great, Vadim, Arkadiusz, Grzegorz... ?
I had a long discussion with Jiri about this and we agreed finally
that dpll_mode represents a reference (input pin) selection strategy
mode and not a DPLL device running mode.
Long discussion? I see 2 emails ;) Let's hear from others.
(thanks for the link BTW, _if_ there's a v6 please put it in the cover
letter)
I called him... he explained me 'why?' in detail.
I also appreciate others' opinion.
Well, NCO mode means manual operation of frequency tuning. Does it mean
that different tunings may be applied to different out pins of DPLL
device? My assumption that it's not possible, and in this case NCO is
property/mode of DPLL device rather than single pin.
The NCO pin is only one per device... When it is connected, then the
device the pin is connected to is switched to NCO mode. In this mode
the device is not locked to any input reference and the driver allows
tuning of the DPLL frequency manually via PTP interface.
Such tuning is applied only to output pins associated with this device
but not on others.
Examples:
DPLL0 is driving output 0-3 and DPLL1 is driving output 4-7.
Then if you switch the DPLL0 to NCO mode (makes NCO pin connected to it)
then frequency tuning (via PTP) has only influence on output 0-3 (the
same tuning is applied). Outputs 4-7 are not touched as they are driven
by DPLL1 (that can be locked to some input reference).
If you switch both DPLLs to NCO, then frequency tuning for DPLL0 affects
output 0-3 and tuning for DPLL1 output 4-7.
Thanks,
Ivan