Re: [Linuxptp-users] ptp4l/phc2sys: Linux 'date' incorrect

[Harold L. <hla...@pi...>]

Richard,

Thanks for the quick response. Did a search on the web for 'ptp4l man' and came up with a number of man documents that didn't have 'step_theshold' shown so I suspect they're from older linuxptp releases. Came across a URL document that shows 'step_theshold' being 1.0 by default but suspect this is incorrect due to your earlier response (or they have a default configuration file that is being referenced) but the document is a good reference for the specification/setting of ptp4l configuration file parameters. 

Do you have a 'step_theshold' value you would recommend (for that matter do you have a default configuration file recommendation)?

What is the latest release of 'linuxptp' (a new version due to be released anytime soon)?

Thanks,
Harold


URL: http://nineways.co.uk/DMA-uCLinux_ptp1588_RG_1.0.pdf

AMBA DMA Controller
uCLinux PTP-1588 Reference Guide

~]# ptp4l -f /ptp/defult.cfg 
A configuration file equivalent to the -i /dev/mtip3 -m -S options shown above would look as follows: 
~]# cat default.cfg 

[global] 
verbose 1 
time_stamping software 
[/dev/mtip3] 
The actual default.cfg contents are as follows: 
[global] 
twoStepFlag 1 
slaveOnly 0 
priority1 128 
priority2 128 
domainNumber 0 
clockClass 248 
clockAccuracy 0xFE 
offsetScaledLogVariance 0xFFFF 
free_running 0 
freq_est_interval 1 
logAnnounceInterval 1 
logSyncInterval 0 
logMinDelayReqInterval 0 
logMinPdelayReqInterval 0 
announceReceiptTimeout 3 
syncReceiptTimeout 0 
delayAsymmetry 0 
fault_reset_interval 4 
neighborPropDelayThresh 20000000 
assume_two_step 0 
logging_level 6 
path_trace_enabled 0 
follow_up_info 1 
tx_timestamp_timeout 1 
use_syslog 0 
verbose 1 
summary_interval 0 
kernel_leap 1 
pi_proportional_const 0.0 
pi_integral_const 0.0 
pi_proportional_scale 0.0 
pi_proportional_exponent -0.3 
pi_proportional_norm_max 0.7 
pi_integral_scale 0.0 
pi_integral_exponent 0.4 
pi_integral_norm_max 0.3 
step_threshold 1 
first_step_threshold 0.00005 
max_frequency 900000000 
clock_servo pi 
sanity_freq_limit 200000000 
ntpshm_segment 0 
transportSpecific 0x0 
ptp_dst_mac 01:1B:19:00:00:00 
p2p_dst_mac 01:80:C2:00:00:0E 
udp6_scope 0x0 
uds_address /etc/uds/ptp4l 
delay_mechanism Auto 
time_stamping hardware 
delay_filter moving_median 
delay_filter_length 10 
productDescription ;product name; 
revisionData ;MorethanIP-SWITCH/MAC-V0.1; 
manufacturerIdentity FF:01:22 
userDescription Hardware timer counter in Fabric/Hardware [FF:01:22] - MTIP/NW identifier 
timeSource 0xA0 [/dev/mtip3]


-----Original Message-----
From: Richard Cochran [mailto:ric...@gm...] 
Sent: Tuesday, September 15, 2015 1:38 PM
To: Harold Lapprich <hla...@pi...>
Cc: lin...@li...
Subject: Re: [Linuxptp-users] ptp4l/phc2sys: Linux 'date' incorrect

On Tue, Sep 15, 2015 at 04:32:09PM +0000, Harold Lapprich wrote:
> How does one get a system to recover quickly from this type of issue 
> (i.e., 20 - 30 minutes is unreasonable and powering the unit ON/OFF 
> isn't an option)?

Use the step_threshold configuration option.  From the man page:

       step_threshold
              The maximum offset the servo will correct by changing the  clock
              frequency  instead  of  stepping the clock. When set to 0.0, the
              servo will never step the clock except on start. It's  specified
              in  seconds.  The default is 0.0.  This option used to be called
              pi_offset_const.

Richard