If the previously set PEROUT is already active, updating it will cause the new PEROUT to start immediately instead of at the specified time. This is because fep->reload_period is updated whithout check whether the PEROUT is enabled, and the old PEROUT is not disabled. Therefore, the pulse period will be updated immediately in the pulse interrupt handler fec_pps_interrupt(). Currently, the driver does not support directly updating PEROUT and it will make the logic be more complicated. To fix the current issue, add a check before enabling the PEROUT, the driver will return an error if PEROUT is enabled. If users wants to update a new PEROUT, they should disable the old PEROUT first. Fixes: 350749b909bf ("net: fec: Add support for periodic output signal of PPS") Signed-off-by: Wei Fang <wei.fang@nxp.com> Link: https://patch.msgid.link/20251125085210.1094306-3-wei.fang@nxp.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>