Recently the Linux kernel's PTP Hardware Clock interface was expanded
to include a "write phase" mode where the clock servo in implemented
in hardware. This mode hearkens back to the tradition ntp_adjtime
interface, passing a measured offset into the kernel's servo.
This patch adds a new configuration option and logic to support the
write phase mode.
Because the hardware's adjustment bandwidth may be limited, this mode
is only activated when the servo reaches SERVO_LOCKED_STABLE state, in
order to achieve reasonably fast locking times. Users may control the
SERVO_LOCKED_STABLE state by configuring 'servo_offset_threshold' and
'servo_num_offset_values' accordingly.
Example configuration file highlights:
unicast_listen 1
logSyncInterval 0
logMinDelayReqInterval 0
first_step_threshold 0.001000000
step_threshold 0
clock_servo pi
write_phase_mode 1
servo_offset_threshold 50
servo_num_offset_values 10
tsproc_mode raw
Signed-off-by: Vincent Cheng <vincent.cheng.xh@renesas.com>
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
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