Re: [PATCH 1/3] net: macb: Fix PTP one step sync support

From: Jakub Kicinski <kuba@kernel.org>
To: Harini Katakam <harinik@xilinx.com>
Cc: Harini Katakam <harini.katakam@xilinx.com>,
	Nicolas Ferre <nicolas.ferre@microchip.com>,
	David Miller <davem@davemloft.net>,
	Richard Cochran <richardcochran@gmail.com>,
	Claudiu Beznea <claudiu.beznea@microchip.com>,
	Paolo Abeni <pabeni@redhat.com>, netdev <netdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Michal Simek <michal.simek@xilinx.com>,
	Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Subject: Re: [PATCH 1/3] net: macb: Fix PTP one step sync support
Date: Tue, 17 May 2022 22:06:03 -0700	[thread overview]
Message-ID: <20220517220603.36eec66e@kernel.org> (raw)
In-Reply-To: <CAFcVEC+qdouQ+tJdBG_Vv8QsaUX99uFtjKnB5WwQawA1fxmgEQ@mail.gmail.com>

On Wed, 18 May 2022 09:53:29 +0530 Harini Katakam wrote:
> On Wed, May 18, 2022 at 8:12 AM Jakub Kicinski <kuba@kernel.org> wrote:
> >
> > On Tue, 17 May 2022 13:02:57 +0530 Harini Katakam wrote:  
> > > PTP one step sync packets cannot have CSUM padding and insertion in
> > > SW since time stamp is inserted on the fly by HW.
> > > In addition, ptp4l version 3.0 and above report an error when skb
> > > timestamps are reported for packets that not processed for TX TS
> > > after transmission.
> > > Add a helper to identify PTP one step sync and fix the above two
> > > errors.
> > > Also reset ptp OSS bit when one step is not selected.
> > >
> > > Fixes: ab91f0a9b5f4 ("net: macb: Add hardware PTP support")
> > > Fixes: 653e92a9175e ("net: macb: add support for padding and fcs computation")  
> >
> > Please make sure to CC authors of the patches under fixes.
> > ./scripts/get_maintainer should point them out.  
> 
> Thanks for the review.
> Rafal Ozieblo <rafalo@cadence.com> is the author of the first Fixes
> patch but that
> address hasn't worked in the last ~4 yrs.
> I have cced Claudiu and everyone else from the maintainers
> (Eric Dumazet <edumazet@google.com> also doesn't work)

I see, thanks, added Rafal's email to the ignore list, 
I'm quite sure Eric's email address works.

> > > @@ -1158,13 +1192,14 @@ static int macb_tx_complete(struct macb_queue *queue, int budget)
> > >
> > >                       /* First, update TX stats if needed */
> > >                       if (skb) {
> > > -                             if (unlikely(skb_shinfo(skb)->tx_flags &
> > > -                                          SKBTX_HW_TSTAMP) &&
> > > -                                 gem_ptp_do_txstamp(queue, skb, desc) == 0) {
> > > -                                     /* skb now belongs to timestamp buffer
> > > -                                      * and will be removed later
> > > -                                      */
> > > -                                     tx_skb->skb = NULL;
> > > +                             if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) &&  
> >
> > ptp_oss already checks if HW_TSTAMP is set.  
> 
> The check for SKBTX_HW_TSTAMP is required here universally and not
> just inside ptp_oss.
> I will remove the redundant check in ptp_oss instead. Please see the
> reply below.

But then you need to add this check in the padding/fcs call site and
the place where NOCRC is set. If you wrap the check for SKBTX_HW_TSTAMP
in the helper with likely() and remove the inline - will the compiler
not split the function and inline just that check? And leave the rest
as a functionname.part... thing?