Re: [Linuxptp-users] [Linuxptp-devel] Debugging ptp4l

[Drasko D. <dra...@gm...>]

On Thu, May 30, 2013 at 10:10 PM, Keller, Jacob E
<jac...@in...> wrote:
>> -----Original Message-----
>> From: Richard Cochran [mailto:ric...@gm...]
>> Sent: Thursday, May 30, 2013 10:54 AM
>> To: Drasko DRASKOVIC
>> Cc: lin...@li...
>> Subject: Re: [Linuxptp-users] [Linuxptp-devel] Debugging ptp4l
>>
>> On Thu, May 30, 2013 at 07:34:45PM +0200, Drasko DRASKOVIC wrote:
>> >
>> > What is :
>> > ptp4l[234.056]: poll tx timestamp failed: No such file or directory
>> > ptp4l[234.056]: port 1: send delay request failed
>> >
>> >
>> > and how is it different than :
>> > ptp4l[106753.952]: poll tx timestamp failed: Success
>> > ptp4l[106753.952]: port 1: send sync failed
>> > ptp4l[106753.952]: port 1: MASTER to FAULTY on FAULT_DETECTED
>> (FT_UNSPECIFIED)
>> >
>> > that I was seeing on MASTER side before skb_tx_timestamp(skb) was
>> > inserted in the driver ?
>>
>> I guess that the wireless stack returns ENOENT because it doesn't have
>> an error queue for the time stamps, or something like that.
>>
>> HTH,
>> Richard
>>
>
> Yes, this is most likely the reason, but I also don't know for sure..
>
> Drasko,
>
> There are a lot of issues with enabling timestamping in the wireless devices. The framework which exists for Ethernet does not necessarily translate to wireless, and it would require a lot more work to enable it. Neither myself or Richard currently has the time, hardware, or experience to really debug this. This is really beyond the scope of the linuxptp mailing lists, as ptp4l is primarily designed with Ethernet in mind.
>
> I am not sure where best to make a thread where you could get the help you need....
>
> - Jake

Hello Richard, Jake,
I understand that these questions are beyond the scope of this dev
list and I will switch to users list instead (did not saw it before).

I tried first using linux-ptp with ethernet, just to check out how it
works and understand how to set-up environment. Pandaboard uses
smsc95xx ETH driver
(http://lxr.free-electrons.com/source/drivers/net/usb/smsc95xx.c),
which seems to have implemented SW timestamping and ptp4l gives quite
good performance (20 - 40 uS clock offsets measured with scope).

However, I will have only WiFi connection in the future, so I am
trying to set-up similar thing (with performance penalty off course),
to see how far I can go with this method.

As I mentioned before, Pandaboard uses this WiFi driver :
https://github.com/garwedgess/ti-wlan/tree/master/compat-wireless-wl12xx/drivers/net/wireless/wl12xx,
and I just inserted  skb_tx_timestamp(skb); inside of
wl1271_prepare_tx_frame() here
https://github.com/garwedgess/ti-wlan/blob/master/compat-wireless-wl12xx/drivers/net/wireless/wl12xx/tx.c#L443.
This does not seem to work quite well, so I will proceed with my
debugging and will keep you informed on users list.

Thank you again for your help.

Best regards,
Drasko