Re: [Linuxptp-devel] [PATCH v3 00/11] synce4l: add software for Synchronous Ethernet

[Aya L. <ay...@nv...>]

On 5/30/2022 10:34 PM, Arkadiusz Kubalewski wrote:
> synce4l is a software implementation of Synchronous Ethernet (Sync-E)
> according to ITU-T Recommendation G.8264. The design goal is to provide
> logic to supported hardware by processing Ethernet Synchronization
> Messaging Channel (ESMC) and control Digital Phase Locked Loop (DPLL)
We should use EEC rather than DPLL (more abstract less HW related)
> clock on Network Card Interface (NIC).
> 
> Application can operate in two mutually exclusive modes. If both modes
> are configured simultaneously, the external input takes precedence over
> internal one (internal is disabled implicitly).
AFAIU there is one selection process which regards all the sources and 
select according to the quality/priority.
What is the benefit of two mutually exclusive modes?
> 
> External input mode
> If synce4l is configured to run in "external input" mode, then DPLL
> needs to have external 1PPS source attached (GPS or another generator).
> In this scenario synce4l always broadcasts clock quality level (QL)
> defined in configuration file. Additionally, for this mode
> incoming Sync-E frames do not participate in best source selection
> algorithm for DPLL.
> 
> Internal input mode
Lets use the standard (G.8264 - Annex A) naming of traffic reference 
source. Internal may refer internal oscillator.
> In "internal input" mode incoming Sync-E frames are processed and best
> clock source is extracted from the link having the best quality level.
> synce4l configures such "best quality" port as a source to recover
> clock for DPLL. The recovered QL is broadcasted to all other interfaces
> then. An external clock cannot be used in this mode.
> 
> Hardware
> synce4l is not bound to any specific NIC hardware.
In this level HW should be hidden totally - please see my comment in 
patch #5
> 
> Theoretically any NIC could be used for enabling Sync-E device in
Lets use SyncE and not Sync-E
> External input mode - the NIC in this mode is in leader role (similar
> to Grand Master role in PTP), providing its Quality Level information
> in ESMC frames to its neighbors.
How do we monitor the quality and validity of an external source?
> It will not syntonize to any of its neighbor ports, since RX frames
> are not monitored. Only other Sync-E enabled neighbor ports could
> recover clock from that peer and syntonize to it.
> Practically this mode shall be used only if the NIC PHY ports are fed
> with stable and reliable frequency clock, Quality Level values that are
> sent to the peers are configured by the user. This is user
> responsibility to decide and set proper Quality-Level value for the
> device, corresponding to the quality of frequency clock generator of
> used hardware.
> 
> When enabling Internal input mode, the NIC must be a device that
> actually, supports Synchronous Ethernet, which means it is able to
> syntonize frequency of all configured ports within the device
> to one chosen port - clock is recovered from its RX path, then is fed
> to other ports with Phase-Locked Loop (PLL) circuit powering clock of
> other ports.
> The NIC driver or dedicated software must provide a user with ability
> to:
> 
> obtain current state of a DPLL used to syntonize the ports
> select one of the ports as a candidate for clock recovery.
> Both abilities are configurable in config file - the user must provide
> a shell commands - as explained in manual and descriptions inside of
> example config file.
> 
> Arkadiusz Kubalewski (11):
>    synce4l: add config knobs for SyncE
>    synce4l: add synce in interface and util code
>    synce4l: add esmc_socket interface
>    synce4l: add synce_clock interface
>    synce4l: add synce_dev interface
>    synce4l: add synce_dev_ctrl interface
>    synce4l: add synce_port interface
>    synce4l: add synce_port_ctrl interface
>    synce4l: add synce_msg interface
>    synce4l: add synce_transport interface
>    synce4l: add synce4l application
> 
>   .gitignore                |    1 +
>   README.org                |    2 +
>   config.c                  |  197 +++++--
>   config.h                  |    8 +
>   configs/synce.cfg         |  194 +++++++
>   esmc_socket.c             |   99 ++++
>   esmc_socket.h             |   42 ++
>   interface.c               |   29 +-
>   interface.h               |   24 +
>   makefile                  |    9 +-
>   synce4l.8                 |  239 ++++++++
>   synce4l.c                 |  132 +++++
>   synce4l_README.md         |  194 +++++++
>   synce_clock.c             |  284 +++++++++
>   synce_clock.h             |   40 ++
>   synce_dev.c               |  622 ++++++++++++++++++++
>   synce_dev.h               |   64 ++
>   synce_dev_ctrl.c          |  153 +++++
>   synce_dev_ctrl.h          |   64 ++
>   synce_msg.c               |  259 +++++++++
>   synce_msg.h               |  174 ++++++
>   synce_msg_private.h       |   87 +++
>   synce_port.c              |  491 ++++++++++++++++
>   synce_port.h              |  184 ++++++
>   synce_port_ctrl.c         | 1161 +++++++++++++++++++++++++++++++++++++
>   synce_port_ctrl.h         |  165 ++++++
>   synce_transport.c         |  102 ++++
>   synce_transport.h         |   55 ++
>   synce_transport_private.h |   18 +
>   util.c                    |   22 +
>   util.h                    |    8 +
>   31 files changed, 5077 insertions(+), 46 deletions(-)
>   create mode 100644 configs/synce.cfg
>   create mode 100644 esmc_socket.c
>   create mode 100644 esmc_socket.h
>   create mode 100644 synce4l.8
>   create mode 100644 synce4l.c
>   create mode 100644 synce4l_README.md
>   create mode 100644 synce_clock.c
>   create mode 100644 synce_clock.h
>   create mode 100644 synce_dev.c
>   create mode 100644 synce_dev.h
>   create mode 100644 synce_dev_ctrl.c
>   create mode 100644 synce_dev_ctrl.h
>   create mode 100644 synce_msg.c
>   create mode 100644 synce_msg.h
>   create mode 100644 synce_msg_private.h
>   create mode 100644 synce_port.c
>   create mode 100644 synce_port.h
>   create mode 100644 synce_port_ctrl.c
>   create mode 100644 synce_port_ctrl.h
>   create mode 100644 synce_transport.c
>   create mode 100644 synce_transport.h
>   create mode 100644 synce_transport_private.h
>