Kernel/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-12-29 17:25:38 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

ptp: Clarify ptp_clock_info .adjphase expects an internal servo to be used

Browse Source 
.adjphase expects a PHC to use an internal servo algorithm to correct the
provided phase offset target in the callback. Implementation of the
internal servo algorithm are defined by the individual devices.

Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Rahul Rameshbabu 2023-06-12 14:14:52 -07:00 committed by David S. Miller
parent 4931062492
commit a05d070a61
2 changed files with 20 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
Documentation/driver-api/ptp.rst
View File

@ -73,6 +73,22 @@ Writing clock drivers
class driver, since the lock may also be needed by the clock
driver's interrupt service routine.
PTP hardware clock requirements for '.adjphase'
-----------------------------------------------
The 'struct ptp_clock_info' interface has a '.adjphase' function.
This function has a set of requirements from the PHC in order to be
implemented.
* The PHC implements a servo algorithm internally that is used to
correct the offset passed in the '.adjphase' call.
* When other PTP adjustment functions are called, the PHC servo
algorithm is disabled.
**NOTE:** '.adjphase' is not a simple time adjustment functionality
that 'jumps' the PHC clock time based on the provided offset. It
should correct the offset provided using an internal algorithm.
Supported hardware
==================

6
include/linux/ptp_clock_kernel.h
View File

@ -77,8 +77,10 @@ struct ptp_system_timestamp {
* nominal frequency in parts per million, but with a
* 16 bit binary fractional field.
*
* @adjphase: Adjusts the phase offset of the hardware clock.
* parameter delta: Desired change in nanoseconds.
* @adjphase: Indicates that the PHC should use an internal servo
* algorithm to correct the provided phase offset.
* parameter delta: PHC servo phase adjustment target
* in nanoseconds.
*
* @adjtime: Shifts the time of the hardware clock.
* parameter delta: Desired change in nanoseconds.