Re: [PATCH net RESEND 1/2] net: macb: Preserve one-step mode on rejected timestamp requests

[Nicolai Buchwitz <nb@tipi-net.de>]

Hi Kimwoo

On 11.9.2026 10:04, kimwooseok wrote:
> gem_set_hwtst() programs NCR.OSSMODE while processing tx_type, before
> validating rx_filter. An unsupported receive filter can therefore cause
> the operation to return -ERANGE after changing the active transmit 
> mode.
> The cached configuration is not updated, so a subsequent SIOCGHWTSTAMP
> reports the previous transmit mode even though the hardware has 
> changed.
> 
> For example, configure HWTSTAMP_TX_ON with HWTSTAMP_FILTER_ALL, then
> request HWTSTAMP_TX_ONESTEP_SYNC with HWTSTAMP_FILTER_NTP_ALL. The 
> latter
> request fails but enables one-step synchronization. The reverse
> transition can clear one-step mode despite returning the same error.
> 
> Defer programming the one-step mode until both the transmit type and
> receive filter have been validated. Rejected receive filters then leave
> the active transmit mode unchanged.
> 
> Fixes: ab91f0a9b5f4 ("net: macb: Add hardware PTP support")
> Assisted-by: GPT-6 Astra
> Signed-off-by: kimwooseok <5mghybrid@khu.ac.kr>
> ---
> Resending as plain text because the previous webmail submission 
> included
> HTML and quoted and rewrapped the patch. No code changes; the 
> Assisted-by
> trailer now names the tool.
> 
>  drivers/net/ethernet/cadence/macb_ptp.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_ptp.c 
> b/drivers/net/ethernet/cadence/macb_ptp.c
> index e5195d7..51659bb 100644
> --- a/drivers/net/ethernet/cadence/macb_ptp.c
> +++ b/drivers/net/ethernet/cadence/macb_ptp.c
> @@ -418,11 +418,9 @@ int gem_set_hwtst(struct net_device *netdev,
>  	case HWTSTAMP_TX_OFF:
>  		break;
>  	case HWTSTAMP_TX_ONESTEP_SYNC:
> -		gem_ptp_set_one_step_sync(bp, 1);
>  		tx_bd_control = TSTAMP_ALL_FRAMES;
>  		break;
>  	case HWTSTAMP_TX_ON:
> -		gem_ptp_set_one_step_sync(bp, 0);
>  		tx_bd_control = TSTAMP_ALL_FRAMES;
>  		break;
>  	default:
> @@ -460,6 +458,11 @@ int gem_set_hwtst(struct net_device *netdev,
>  		return -ERANGE;
>  	}
> 
> +	if (tstamp_config->tx_type == HWTSTAMP_TX_ONESTEP_SYNC)
> +		gem_ptp_set_one_step_sync(bp, 1);
> +	else if (tstamp_config->tx_type == HWTSTAMP_TX_ON)
> +		gem_ptp_set_one_step_sync(bp, 0);
> +
>  	bp->tstamp_config = *tstamp_config;
> 
>  	if (gem_ptp_set_ts_mode(bp, tx_bd_control, rx_bd_control) != 0)

Reviewed-by: Nicolai Buchwitz <nb@tip-net.de>
Tested-by: Nicolai Buchwitz <nb@tipi-net.de> # Raspberry Pi CM5

Thanks,
Nicolai