Re: [PATCH net v3] net: stmmac: propagate PTP addend and system time programming errors

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Hi Lorenzo,

On 9/29/26 15:10, Lorenzo Bianconi wrote:
> stmmac_update_subsecond_increment() ignores the error returned by
> stmmac_config_addend(), and stmmac_init_tstamp_counter() discards the
> addend and system time programming errors, always returning success. A
> failure to program the addend (PTP_TCR_TSADDREG) or to initialize the
> system time counter (PTP_TCR_TSINIT) is therefore silently swallowed,
> leaving the hardware timestamp counter in a non-running or partially
> configured state while the driver keeps operating as if timestamping
> were up. This matters for TAPRIO/EST offloading, which derives the gate
> base time from the hardware timestamp counter.
> 
> The same hooks are also called from the PHC callbacks: settime64 and
> adjfine drop the error and report success to clock_settime() and
> clock_adjtime(), so a dead PTP reference clock goes unnoticed by
> ptp4l/phc2sys.
> 
> Return error codes from stmmac_update_subsecond_increment(),
> stmmac_init_tstamp_counter(), stmmac_dl_ts_coarse_set() and the
> settime64/adjfine callbacks instead of silently returning success. On
> failure, roll back the partially applied configuration so the hardware
> and the driver bookkeeping stay consistent, and report the reason
> through the devlink extack. Also guard against a zero sub-second
> increment, which would otherwise divide by zero when computing the
> addend.
> 
> Reset the persistent timestamping state (hwts_tx_en, hwts_rx_en,
> tstamp_config, systime_flags and tsfupdt_coarse) when (re)initializing
> timestamping, so a failed init does not leave TX/RX timestamping
> enabled on a counter that never started.
> 
> Fixes: cc4c9001ce31 ("net: stmmac: Switch stmmac_hwtimestamp to generic HW Interface Helpers")
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>

Thanks, this is nice.

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>

Maxime