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From:   "Ismail, Mohammad Athari" <mohammad.athari.ismail@intel.com>
To:     Vladimir Oltean <olteanv@gmail.com>
CC:     Alexandre Torgue <alexandre.torgue@st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        "David S . Miller" <davem@davemloft.net>,
        "Jakub Kicinski" <kuba@kernel.org>, Andrew Lunn <andrew@lunn.ch>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        "Ong, Boon Leong" <boon.leong.ong@intel.com>,
        "Voon, Weifeng" <weifeng.voon@intel.com>,
        "Wong, Vee Khee" <vee.khee.wong@intel.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v2 net-next] net: pcs: Enable pre-emption packet for
 10/100Mbps
Thread-Topic: [PATCH v2 net-next] net: pcs: Enable pre-emption packet for
 10/100Mbps
Thread-Index: AQHXN8w75Vo0bmfsFEyfZYnEbB76e6rBNbyAgAAK1lA=
Date:   Fri, 23 Apr 2021 00:45:25 +0000
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References: <20210422230645.23736-1-mohammad.athari.ismail@intel.com>
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In-Reply-To: <20210422235317.erltirtrxnva5o2d@skbuf>
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Hi Vladimir,

> -----Original Message-----
> From: Vladimir Oltean <olteanv@gmail.com>
> Sent: Friday, April 23, 2021 7:53 AM
> To: Ismail, Mohammad Athari <mohammad.athari.ismail@intel.com>
> Cc: Alexandre Torgue <alexandre.torgue@st.com>; Jose Abreu
> <joabreu@synopsys.com>; David S . Miller <davem@davemloft.net>; Jakub
> Kicinski <kuba@kernel.org>; Andrew Lunn <andrew@lunn.ch>; Heiner Kallweit
> <hkallweit1@gmail.com>; Russell King <linux@armlinux.org.uk>; Ong, Boon
> Leong <boon.leong.ong@intel.com>; Voon, Weifeng
> <weifeng.voon@intel.com>; Wong, Vee Khee <vee.khee.wong@intel.com>;
> netdev@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v2 net-next] net: pcs: Enable pre-emption packet for
> 10/100Mbps
>=20
> Hi Mohammad,
>=20
> On Fri, Apr 23, 2021 at 07:06:45AM +0800, mohammad.athari.ismail@intel.co=
m
> wrote:
> > From: Mohammad Athari Bin Ismail <mohammad.athari.ismail@intel.com>
> >
> > Set VR_MII_DIG_CTRL1 bit-6(PRE_EMP) to enable pre-emption packet for
> > 10/100Mbps by default. This setting doesn`t impact pre-emption
> > capability for other speeds.
> >
> > Signed-off-by: Mohammad Athari Bin Ismail
> > <mohammad.athari.ismail@intel.com>
> > ---
>=20
> What is a "pre-emption packet"?

In IEEE 802.1 Qbu (Frame Preemption), pre-emption packet is used to differe=
ntiate between MAC Frame packet, Express Packet, Non-fragmented Normal Fram=
e Packet, First Fragment of Preemptable Packet, Intermediate Fragment of Pr=
eemptable Packet and Last Fragment of Preemptable Packet.=20

This bit "VR_MII_DIG_CTRL1 bit-6(PRE_EMP)" defined in DesignWare Cores Ethe=
rnet PCS Databook is to allow the IP to properly receive/transmit pre-empti=
on packets in SGMII 10M/100M Modes.

Thanks.