netdev - RE: [PATCH v1 0/4] Add support for DMA timestamp for non-PTP packets

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Date:   Thu, 29 Sep 2022 02:22:28 +0000
From:   "Zulkifli, Muhammad Husaini" <muhammad.husaini.zulkifli@...el.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     "intel-wired-lan@...osl.org" <intel-wired-lan@...osl.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "Gomes, Vinicius" <vinicius.gomes@...el.com>,
        "Gunasekaran, Aravindhan" <aravindhan.gunasekaran@...el.com>,
        "Ahmad Tarmizi, Noor Azura" <noor.azura.ahmad.tarmizi@...el.com>,
        Richard Cochran <richardcochran@...il.com>
Subject: RE: [PATCH v1 0/4] Add support for DMA timestamp for non-PTP packets

Hi Andrew,

Thanks for reviewing. 
Please see my reply in-line.

> -----Original Message-----
> From: Andrew Lunn <andrew@...n.ch>
> Sent: Tuesday, 27 September, 2022 11:27 PM
> To: Zulkifli, Muhammad Husaini <muhammad.husaini.zulkifli@...el.com>
> Cc: intel-wired-lan@...osl.org; netdev@...r.kernel.org;
> davem@...emloft.net; kuba@...nel.org; edumazet@...gle.com; Gomes,
> Vinicius <vinicius.gomes@...el.com>; Gunasekaran, Aravindhan
> <aravindhan.gunasekaran@...el.com>; Ahmad Tarmizi, Noor Azura
> <noor.azura.ahmad.tarmizi@...el.com>
> Subject: Re: [PATCH v1 0/4] Add support for DMA timestamp for non-PTP
> packets
> 
> On Tue, Sep 27, 2022 at 09:06:52PM +0800, Muhammad Husaini Zulkifli
> wrote:
> > The HW TX timestamps created by the NIC via socket options can be
> > requested using the current network timestamps generation capability
> > of SOF_TIMESTAMPING_TX_HARDWARE. The most common users of this
> socket
> > flag is PTP, however other packet applications that require tx
> > timestamps might also ask for it.
> >
> > The problem is that, when there is a lot of traffic, there is a high
> > chance that the timestamps for a PTP packet will be lost if both PTP
> > and Non-PTP packets use the same SOF TIMESTAMPING TX HARDWARE
> causing the tx timeout.
> >
> > DMA timestamps through socket options are not currently available to
> > the user. Because if the user wants to, they can configure the
> > hwtstamp config option to use the new introduced DMA Time Stamp flag
> > through the setsockopt().
> >
> > With these additional socket options, users can continue to utilise HW
> > timestamps for PTP while specifying non-PTP packets to use DMA
> > timestamps if the NIC can support them.
> 
> Although this is not actually for PTP, you probably should Cc: the PTP
> maintainer for patches like this.

Thanks. Added Richard in the CC list.

> 
> 	   Andrew