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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>