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Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/ptp.rst | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/Documentation/driver-api/ptp.rst b/Documentation/driver-api/ptp.rst index 664838ae7776..4552a1f20488 100644 --- a/Documentation/driver-api/ptp.rst +++ b/Documentation/driver-api/ptp.rst @@ -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 ================== |