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[92.34.211.33]) by smtp.gmail.com with ESMTPSA id v2-20020a056512096200b00502e2347ef0sm2793521lft.193.2023.09.27.15.12.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Sep 2023 15:12:59 -0700 (PDT) From: Linus Walleij Date: Thu, 28 Sep 2023 00:12:56 +0200 Subject: [PATCH net-next v3] net: ixp4xx_eth: Support changing the MTU MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20230928-ixp4xx-eth-mtu-v3-1-cb18eaa0edb9@linaro.org> X-B4-Tracking: v=1; b=H4sIAOeoFGUC/3WNywrCMBQFf6Vk7ZU8Wtq48j/ERZJe24CmJYkhU vrvhqwUcTkcZs5GAnqLgZyajXhMNtjFFRCHhphZuQnBjoUJp1xQyQXYvLY5A8YZHvEJhrZs7PG GUnBSpNXjzeYavBCHERzmSK5lmW2Ii3/Vp8Tq/i+aGDCQOAxa0gGZ5ue7dcovx8VPtZX4p9/9+ Lz4QgqjlO47o+mXv+/7G6MyOA/3AAAA To: Krzysztof Halasa , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jacob Keller , Linus Walleij X-Mailer: b4 0.12.3 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As we don't specify the MTU in the driver, the framework will fall back to 1500 bytes and this doesn't work very well when we try to attach a DSA switch: eth1: mtu greater than device maximum ixp4xx_eth c800a000.ethernet eth1: error -22 setting MTU to 1504 to include DSA overhead After locating an out-of-tree patch in OpenWrt I found suitable code to set the MTU on the interface and ported it and updated it. Now the MTU gets set properly. Reviewed-by: Jacob Keller Signed-off-by: Linus Walleij --- Changes in v3: - Fix some coding style and initialization style. - Collect Jacob's review tag. - Link to v2: https://lore.kernel.org/r/20230925-ixp4xx-eth-mtu-v2-1-393caa= b75cb0@linaro.org Changes in v2: - Don't just set min/max MTU: implement the interface for actually changing it as well. - Link to v1: https://lore.kernel.org/r/20230923-ixp4xx-eth-mtu-v1-1-9e88b9= 08e1b2@linaro.org --- drivers/net/ethernet/xscale/ixp4xx_eth.c | 65 ++++++++++++++++++++++++++++= +++- 1 file changed, 64 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/xscale/ixp4xx_eth.c b/drivers/net/etherne= t/xscale/ixp4xx_eth.c index 3b0c5f177447..910094ab553c 100644 --- a/drivers/net/ethernet/xscale/ixp4xx_eth.c +++ b/drivers/net/ethernet/xscale/ixp4xx_eth.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include #include @@ -63,7 +64,15 @@ =20 #define POOL_ALLOC_SIZE (sizeof(struct desc) * (RX_DESCS + TX_DESCS)) #define REGS_SIZE 0x1000 -#define MAX_MRU 1536 /* 0x600 */ + +/* MRU is said to be 14320 in a code dump, the SW manual says that + * MRU/MTU is 16320 and includes VLAN and ethernet headers. + * See "IXP400 Software Programmer's Guide" section 10.3.2, page 161. + * + * FIXME: we have chosen the safe default (14320) but if you can test + * jumboframes, experiment with 16320 and see what happens! + */ +#define MAX_MRU (14320 - VLAN_ETH_HLEN) #define RX_BUFF_SIZE ALIGN((NET_IP_ALIGN) + MAX_MRU, 4) =20 #define NAPI_WEIGHT 16 @@ -1182,6 +1191,54 @@ static void destroy_queues(struct port *port) } } =20 +static int ixp4xx_do_change_mtu(struct net_device *dev, int new_mtu) +{ + struct port *port =3D netdev_priv(dev); + struct npe *npe =3D port->npe; + int framesize, chunks; + struct msg msg =3D {}; + + /* adjust for ethernet headers */ + framesize =3D new_mtu + VLAN_ETH_HLEN; + /* max rx/tx 64 byte chunks */ + chunks =3D DIV_ROUND_UP(framesize, 64); + + msg.cmd =3D NPE_SETMAXFRAMELENGTHS; + msg.eth_id =3D port->id; + + /* Firmware wants to know buffer size in 64 byte chunks */ + msg.byte2 =3D chunks << 8; + msg.byte3 =3D chunks << 8; + + msg.byte4 =3D msg.byte6 =3D framesize >> 8; + msg.byte5 =3D msg.byte7 =3D framesize & 0xff; + + if (npe_send_recv_message(npe, &msg, "ETH_SET_MAX_FRAME_LENGTH")) + return -EIO; + netdev_dbg(dev, "set MTU on NPE %s to %d bytes\n", + npe_name(npe), new_mtu); + + return 0; +} + +static int ixp4xx_eth_change_mtu(struct net_device *dev, int new_mtu) +{ + int ret; + + /* MTU can only be changed when the interface is up. We also + * set the MTU from dev->mtu when opening the device. + */ + if (dev->flags & IFF_UP) { + ret =3D ixp4xx_do_change_mtu(dev, new_mtu); + if (ret < 0) + return ret; + } + + dev->mtu =3D new_mtu; + + return 0; +} + static int eth_open(struct net_device *dev) { struct port *port =3D netdev_priv(dev); @@ -1232,6 +1289,8 @@ static int eth_open(struct net_device *dev) if (npe_send_recv_message(port->npe, &msg, "ETH_SET_FIREWALL_MODE")) return -EIO; =20 + ixp4xx_do_change_mtu(dev, dev->mtu); + if ((err =3D request_queues(port)) !=3D 0) return err; =20 @@ -1374,6 +1433,7 @@ static int eth_close(struct net_device *dev) static const struct net_device_ops ixp4xx_netdev_ops =3D { .ndo_open =3D eth_open, .ndo_stop =3D eth_close, + .ndo_change_mtu =3D ixp4xx_eth_change_mtu, .ndo_start_xmit =3D eth_xmit, .ndo_set_rx_mode =3D eth_set_mcast_list, .ndo_eth_ioctl =3D eth_ioctl, @@ -1488,6 +1548,9 @@ static int ixp4xx_eth_probe(struct platform_device *p= dev) ndev->dev.dma_mask =3D dev->dma_mask; ndev->dev.coherent_dma_mask =3D dev->coherent_dma_mask; =20 + ndev->min_mtu =3D ETH_MIN_MTU; + ndev->max_mtu =3D MAX_MRU; + netif_napi_add_weight(ndev, &port->napi, eth_poll, NAPI_WEIGHT); =20 if (!(port->npe =3D npe_request(NPE_ID(port->id)))) --- base-commit: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d change-id: 20230923-ixp4xx-eth-mtu-c041d7efe932 Best regards, --=20 Linus Walleij