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54e65df8cf
Replace the per-reference frequency offset measurement (which was redundant with measured-frequency) with a direct read of the DPLL's delta frequency offset vs its tracked input reference. The new implementation uses the dpll_df_offset_x register with ref_ofst=1 via the dpll_df_read_x semaphore mechanism. This provides 2^-48 resolution (~3.5 fE) and reports the actual frequency difference between the DPLL and its active input. Switch supported_ffo from DPLL_FFO_PORT_RXTX_RATE to DPLL_FFO_PIN_DEVICE so FFO is reported only in the per-parent context for the active input pin. Use atomic64_t for freq_offset to prevent torn reads on 32-bit architectures between the periodic worker and netlink callbacks. Rewrite ffo_check to compare the cached df_offset converted to PPT instead of using the old per-reference measurement. Remove the ref_ffo_update periodic measurement and the ref ffo field since they are no longer needed. Changes v3 -> v4: - Switch to DPLL_FFO_PIN_DEVICE, remove dpll=NULL guard - Use atomic64_t for freq_offset (torn read on 32-bit) Reviewed-by: Petr Oros <poros@redhat.com> Signed-off-by: Ivan Vecera <ivecera@redhat.com> Link: https://patch.msgid.link/20260511155816.99936-3-ivecera@redhat.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>