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Date:   Sat, 31 Oct 2020 19:02:27 -0700
From:   Richard Cochran <richardcochran@gmail.com>
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     Grygorii Strashko <grygorii.strashko@ti.com>,
        "David S. Miller" <davem@davemloft.net>, netdev@vger.kernel.org,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Sekhar Nori <nsekhar@ti.com>, linux-kernel@vger.kernel.org,
        linux-omap@vger.kernel.org
Subject: Re: [PATCH] net: ethernet: ti: cpsw: disable PTPv1 hw timestamping
 advertisement
Message-ID: <20201101020227.GB2683@hoboy.vegasvil.org>
References: <20201029190910.30789-1-grygorii.strashko@ti.com>
 <20201031114042.7ccdf507@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net>
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On Sat, Oct 31, 2020 at 11:40:42AM -0700, Jakub Kicinski wrote:
> On Thu, 29 Oct 2020 21:09:10 +0200 Grygorii Strashko wrote:
> > The TI CPTS does not natively support PTPv1, only PTPv2. But, as it
> > happens, the CPTS can provide HW timestamp for PTPv1 Sync messages, because
> > CPTS HW parser looks for PTP messageType id in PTP message octet 0 which
> > value is 0 for PTPv1. As result, CPTS HW can detect Sync messages for PTPv1
> > and PTPv2 (Sync messageType = 0 for both), but it fails for any other PTPv1
> > messages (Delay_req/resp) and will return PTP messageType id 0 for them.
> > 
> > The commit e9523a5a32a1 ("net: ethernet: ti: cpsw: enable
> > HWTSTAMP_FILTER_PTP_V1_L4_EVENT filter") added PTPv1 hw timestamping
> > advertisement by mistake, only to make Linux Kernel "timestamping" utility
> > work, and this causes issues with only PTPv1 compatible HW/SW - Sync HW
> > timestamped, but Delay_req/resp are not.
> > 
> > Hence, fix it disabling PTPv1 hw timestamping advertisement, so only PTPv1
> > compatible HW/SW can properly roll back to SW timestamping.
> > 
> > Fixes: e9523a5a32a1 ("net: ethernet: ti: cpsw: enable HWTSTAMP_FILTER_PTP_V1_L4_EVENT filter")
> > Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
> 
> CC: Richard

Acked-by: Richard Cochran <richardcochran@gmail.com>