Re: [Linuxptp-users] How to properly use twoStepFlag=0

[Timo K. <tko...@ci...>]

Dear Jake,

thanks for the fast reply:

On 11.01.19 18:49, Keller, Jacob E wrote:
> On Fri, 2019-01-11 at 18:03 +0100, Timo Korthals wrote:
>> Dear ptp4l-devs,
>>
> Hi,
>
>> we try to sync embedded devices, which are only capable of
>> PTP_TWO_STEP=FALSE (aka twoStepFlag=0 aka one-way-sync aka
>> PTP_Sync=1) syncing, with our Ubuntu Linux host (System overview
>> below).
>> When we run the self build ptp4l via "./ptp4l -m -l7 -2 -H -i enp0s25
>> -E -f /etc/ptp4l.conf" (see config etc. below), the execution hangs
>> for all ptp4l versions > 1.7 at "INITIALIZING to LISTENING on
>> INIT_COMPLETE".
>> If we comment the corresponding line [1] where ptp4l hangs, its start
>> sending the SYNC_MESSAGE etc. and the log goes on with:
>>
> It sounds like your device driver (and possibly kernel changes, I don't
> remember offhand) needs to support the one step configurations. We
> can't help you with your device driver, especially if it's not
> public/open-source.

The Kernel is the vanilla Ubuntu 4.18 Kernel from canonical's ppa for 
Ubuntu 18.04: 
https://packages.ubuntu.com/bionic/kernel/linux-image-4.18.0-13-generic
All flags should be alright since ptp4l compiles with 
-DHAVE_ONESTEP_SYNC: 
https://github.com/richardcochran/linuxptp/blob/5219b6417faa5248e6093828732ab9fc713b82be/incdefs.sh#L82
The Linux igb driver for this NIC is pretty open source I guess: 
https://github.com/torvalds/linux/tree/master/drivers/net/ethernet/intel/igb

>
> Specifically you're looking for HWTSTAMP_TX_ONESTEP_SYNC. Your kernel
> must be new enough to support the field. Additionally, you will need to
> have your driver updated to correctly enable the request for
> HWTSTAMP_TX_ONESTEP_SYNC.
Ok, that's maybe a thing since no intel driver in the Linux Kernel 
supports this field: 
https://github.com/torvalds/linux/search?q=HWTSTAMP_TX_ONESTEP_SYNC&unscoped_q=HWTSTAMP_TX_ONESTEP_SYNC
The two other chips supporting ONESTEP_SYNC are the TI dp83640 and the 
Microchip LAN7430/1.
However, I only found chip samples but no buyable networkcards having 
these chips.
Does someone know network cards with these chips or at least other 
network cards with HWTSTAMP_TX_ONESTEP_SYNC support?
>
> Note that as far as I'm aware this only works for sync packets, and no
> kernel support for one-step of other messages has been written. This is
> primarly because no hardware has been widely available to test such a
> feature. (i.e. one-step syncing of peer delay messages)
Ok, so I only need the SYNC messages.
However, since removing the line [1] starts one-way syncing, wouldn't it 
be a feasable way to do it in software (with the lack of precision)?
There is just the copy of the timestamps missing, right?
>
> Hope this helps.
>
> Regards,
> Jake
Greetings,
Timo

-- 

Timo Korthals, M.Sc.
Universität Bielefeld
AG Kognitronik & Sensorik
Exzellenzcluster Cognitive Interaction Technology (CITEC)
Inspiration 1 (Zehlendorfer Damm 201)
33619 Bielefeld - Germany

Office  : 3.413
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