diff options
| author | Ivan Vecera <ivecera@redhat.com> | 2026-01-26 17:22:51 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-01-29 18:21:16 -0800 |
| commit | bc443c253fcdd2636e2a29fde3f749d39d479cf0 (patch) | |
| tree | a0c777d02f0000b43a9cccdc5de662a5412d6018 /Documentation/netlink | |
| parent | b3827c91cc9979fe04d99e016fb9c5f6260f29a0 (diff) | |
dpll: expose fractional frequency offset in ppt
Currently, the dpll subsystem exports the fractional frequency offset
(FFO) in parts per million (ppm). This granularity is insufficient for
high-precision synchronization scenarios which often require parts per
trillion (ppt) resolution.
Add a new netlink attribute DPLL_A_PIN_FRACTIONAL_FREQUENCY_OFFSET_PPT
to expose the FFO in ppt.
Update the dpll netlink core to expect the driver-provided FFO value
to be in ppt. To maintain backward compatibility with existing userspace
tools, populate the legacy DPLL_A_PIN_FRACTIONAL_FREQUENCY_OFFSET
attribute by dividing the new ppt value by 1,000,000.
Update the zl3073x and mlx5 drivers to provide the FFO value in ppt:
- zl3073x: adjust the fixed-point calculation to produce ppt (10^12)
instead of ppm (10^6).
- mlx5: scale the existing ppm value by 1,000,000.
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://patch.msgid.link/20260126162253.27890-1-ivecera@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'Documentation/netlink')
| -rw-r--r-- | Documentation/netlink/specs/dpll.yaml | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/netlink/specs/dpll.yaml b/Documentation/netlink/specs/dpll.yaml index b55afa77eac4..3dd48a32f783 100644 --- a/Documentation/netlink/specs/dpll.yaml +++ b/Documentation/netlink/specs/dpll.yaml @@ -446,6 +446,16 @@ attribute-sets: doc: | Granularity of phase adjustment, in picoseconds. The value of phase adjustment must be a multiple of this granularity. + - + name: fractional-frequency-offset-ppt + type: sint + doc: | + The FFO (Fractional Frequency Offset) of the pin with respect to + the nominal frequency. + Value = (frequency_measured - frequency_nominal) / frequency_nominal + Value is in PPT (parts per trillion, 10^-12). + Note: This attribute provides higher resolution than the standard + fractional-frequency-offset (which is in PPM). - name: pin-parent-device @@ -628,6 +638,7 @@ operations: - phase-adjust-max - phase-adjust - fractional-frequency-offset + - fractional-frequency-offset-ppt - esync-frequency - esync-frequency-supported - esync-pulse |