Re: [PATCH net-next 1/4] net: macb: Preserve timestamp settings on rejected requests

[Nicolai Buchwitz]

On 22.9.2026 11:10, Kim Wooseok via B4 Relay wrote:
> From: Kim Wooseok <5mghybrid@xxxxxxxxx>
>
> gem_set_hwtst() can reject a request after changing the TX one-step
> setting, because it programs the TX mode before checking the RX
> filter. The call returns -ERANGE, but the hardware may no longer match
> the cached configuration.
>
> Validate both settings first and keep the adjusted RX filter local
> until validation succeeds. Then apply the register settings and update
> the configuration. A rejected request now leaves the hardware, the
> caller's settings and the cached configuration unchanged.
>
> Protect the NCR read-modify-write with bp->lock, keeping the descriptor
> writes and cache update in the same section. With the register writes
> now in the setter, remove gem_ptp_set_one_step_sync() and
> gem_ptp_set_ts_mode().
>
> Fixes: ab91f0a9b5f4 ("net: macb: Add hardware PTP support")
> Assisted-by: GPT-6 Astra
> Signed-off-by: Kim Wooseok <5mghybrid@xxxxxxxxx>
> ---
>  drivers/net/ethernet/cadence/macb_ptp.c | 61 
> ++++++++++++++-------------------
>  1 file changed, 25 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/net/ethernet/cadence/macb_ptp.c 
> b/drivers/net/ethernet/cadence/macb_ptp.c
> index 14ae57fa0..4dbb6daa6 100644
> --- a/drivers/net/ethernet/cadence/macb_ptp.c
> +++ b/drivers/net/ethernet/cadence/macb_ptp.c

> [...]

>  int gem_set_hwtst(struct net_device *netdev,
>  		  struct kernel_hwtstamp_config *tstamp_config,
>  		  struct netlink_ext_ack *extack)
>  {
> +	u32 ncr_mask = 0;
>  	enum macb_bd_control tx_bd_control = TSTAMP_DISABLED;
>  	enum macb_bd_control rx_bd_control = TSTAMP_DISABLED;
> +	int rx_filter = tstamp_config->rx_filter;
>  	struct macb *bp = netdev_priv(netdev);
> +	unsigned long flags;
> +	u32 ncr_bits = 0;
>  	u32 regval;

Please re-order to keep RCS [1]

> [...]

[1] 
https://www.kernel.org/doc/html/v6.2/process/maintainer-netdev.html#local-variable-ordering-reverse-xmas-tree-rcs

With the above fixed:

Reviewed-by: Nicolai Buchwitz <nb@xxxxxxxxxxx>

Thanks,
Nicolai