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[204.195.123.141]) by smtp.gmail.com with ESMTPSA id b2-20020a056a00114200b006e6b7124b33sm8372023pfm.209.2024.03.18.14.42.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Mar 2024 14:42:13 -0700 (PDT) Date: Mon, 18 Mar 2024 14:42:10 -0700 From: Stephen Hemminger To: Damodharam Ammepalli Cc: Thomas Monjalon , Dengdui Huang , dev@dpdk.org, ferruh.yigit@amd.com, aman.deep.singh@intel.com, yuying.zhang@intel.com, andrew.rybchenko@oktetlabs.ru, liuyonglong@huawei.com, fengchengwen@huawei.com, haijie1@huawei.com, lihuisong@huawei.com Subject: Re: [PATCH 0/3] support setting lanes Message-ID: <20240318144210.2b14bd5b@hermes.local> In-Reply-To: References: <20240312075238.3319480-1-huangdengdui@huawei.com> <1759403.vCJZsxu672@thomas> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Mon, 18 Mar 2024 14:26:33 -0700 Damodharam Ammepalli wrote: > On Mon, Mar 18, 2024 at 7:56=E2=80=AFAM Thomas Monjalon wrote: > > > > 12/03/2024 08:52, Dengdui Huang: =20 > > > Some speeds can be achieved with different number of lanes. For examp= le, > > > 100Gbps can be achieved using two lanes of 50Gbps or four lanes of 25= Gbps. > > > When use different lanes, the port cannot be up. =20 > > > > I'm not sure what you are referring to. > > I suppose it is not PCI lanes. > > Please could you link to an explanation of how a port is split in lanes? > > Which hardware does this? > > > > > > =20 > This is a snapshot of 100Gb that the latest BCM576xx supports. > 100Gb (NRZ: 25G per lane, 4 lanes) link speed > 100Gb (PAM4-56: 50G per lane, 2 lanes) link speed > 100Gb (PAM4-112: 100G per lane, 1 lane) link speed >=20 > Let the user feed in lanes=3D< integer value> and the NIC driver decides > the matching combination speed x lanes that works. In future if a new spe= ed > is implemented with more than 8 lanes, there wouldn't be a need > to touch this speed command. Using separate lane command would > be a better alternative to support already shipped products and only new > drivers would consider this lanes configuration, if applicable. >=20 The DPDK does not need more driver specific knobs. Shouldn't the PMD be able to auto negotiate the speed? What does Linux do?