Subject: Re: [PATCH net-next] sfc: add transmit timestamping support

From: Breno Leitao <[email-masked]>
Date: Fri, 27 Mar 2026 03:29:10 -0700

On Thu, Mar 26, 2026 at 06:39:51PM -0700, Jakub Kicinski wrote:
> On Wed, 25 Mar 2026 02:35:12 -0700 Breno Leitao wrote:
> > On Tue, Mar 24, 2026 at 05:08:21PM +0100, Izabela Bakollari wrote:
> > > Enable software TX Timestamping. The out of tree driver 
> > > also implements this.  
> > 
> > "The out of tree driver also implements this" is not the most technical
> > justification.
> 
> +1 it's an odd thing to put in the commit msg.
> Please fix and repost (keep Ed's tag)
> 
> > > diff --git a/drivers/net/ethernet/sfc/ethtool.c b/drivers/net/ethernet/sfc/ethtool.c
> > > index 362388754a29..c0038b942913 100644
> > > --- a/drivers/net/ethernet/sfc/ethtool.c
> > > +++ b/drivers/net/ethernet/sfc/ethtool.c
> > > @@ -231,6 +231,8 @@ static int efx_ethtool_get_ts_info(struct net_device *net_dev,
> > >  {
> > >  	struct efx_nic *efx = efx_netdev_priv(net_dev);
> > >  
> > > +	ts_info->so_timestamping = SOF_TIMESTAMPING_TX_SOFTWARE;  
> > 
> > Don't you need to append SOF_TIMESTAMPING_TX_SOFTWARE instead of
> > assinging it?
> > 
> > 	ts_info->so_timestamping |= SOF_TIMESTAMPING_TX_SOFTWARE;
> 
> Either way is fine IMHO unless you see a specific reason Breno?

No specific reason, it is more a nit.

so_timestamping is always zero-initialized before the callback is called,
meaning = and |= are functionally equivalent today.

That said, I see these callbacks setting fields in so_timestamping, and not
overwriting it, given it does it later with it.

  ts_info->so_timestamping |= (SOF_TIMESTAMPING_TX_HARDWARE |
                               SOF_TIMESTAMPING_RX_HARDWARE |
                               SOF_TIMESTAMPING_RAW_HARDWARE);

But again, it makes no difference in here, given the value is already zero.