Hi,
I am trying to achieve precise time synchronization via wifi interface.
I used intel AX201 card, certified with TimeSync, 802.11v, mc. So I
assume it has the capability to do hardware time stamp when running
applications like linux ptp (http://linuxptp.sourceforge.net/) and gptp
(https://github.com/Avnu/gptp). However I get error that seems to
suggest the timestamp mode is not supported.
After reading some source code, I discover that the /ptp4l/ application,
or /gptp/, or /ethtool/ /-T/ , they all use a system call /ioctl/, which
uses ethtool_ops call back to determine whether the hardware can do
software/hardware timestamp.
However when searching in the driver/net/wireless/iwlwifi directory, I
don't see anywhere /ethtool_ops/ is being implemented in the driver. So
this most likely is why all user space tools I tried seem to determine
the card cannot do hardware and also software (driver level) transmit
timestamp.
Can someone tell me how I could run ptp like application to fully make
use of the Timesync feature of intel card?
Some more details below:
root@localhost:/debug/tracing# ethtool -i wlp2s0
driver: iwlwifi
version: 5.4.6-050406-generic
firmware-version: 48.4fa0041f.0
expansion-rom-version:
bus-info: 0000:02:00.0
supports-statistics: yes
supports-test: no
supports-eeprom-access: no
supports-register-dump: no
supports-priv-flags: no
root@localhost:/debug/tracing# ethtool -T wlp2s0
Time stamping parameters for wlp2s0:
Capabilities:
software-receive (SOF_TIMESTAMPING_RX_SOFTWARE)
software-system-clock (SOF_TIMESTAMPING_SOFTWARE)
PTP Hardware Clock: none
Hardware Transmit Timestamp Modes: none
Hardware Receive Filter Modes: none
Wei Liu <[email protected]> writes:
> Hi,
>
> I am trying to achieve precise time synchronization via wifi
> interface.
Erm, good luck with that? :)
You do realise that there's a whole bunch of stuff going on below the
driver level (listen-before-send, etc) that makes 'precise' timing (as
in microsecond-accuracy like ptp)... shall we just say challenging?
-Toke
Hi Toke,
Yes, it is challenging, but IEEE802.1AS already takes consideration of
IEEE802.11 MAC. So I count on the standardization to take care of the
challenge :)
Point being that the Intel AX201 card claims Timesync feature
(https://www.mouser.com/pdfDocs/wi-fi-6-ax201-module-brief.pdf), which
is based on IEEE802.1AS. So there must be some way to run gptp like
application on the AX201 intel card.
I appreciate any help here if someone has relevant experiences.
Best,
Wei
On 3/5/2020 12:29 PM, Toke Høiland-Jørgensen wrote:
> Wei Liu <[email protected]> writes:
>
>> Hi,
>>
>> I am trying to achieve precise time synchronization via wifi
>> interface.
> Erm, good luck with that? :)
>
> You do realise that there's a whole bunch of stuff going on below the
> driver level (listen-before-send, etc) that makes 'precise' timing (as
> in microsecond-accuracy like ptp)... shall we just say challenging?
>
> -Toke
>