Messages in this thread Patch in this message | | | From | Linus Walleij <> | Date | Thu, 05 Oct 2023 00:43:53 +0200 | Subject | [PATCH net-next v4] net: ixp4xx_eth: Support changing the MTU |
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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 <jacob.e.keller@intel.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- Changes in v4: - Rebase on the merged patch "net: ixp4xx_eth: Specify min/max MTU" so it can be easily applied. - Link to v3: https://lore.kernel.org/r/20230928-ixp4xx-eth-mtu-v3-1-cb18eaa0edb9@linaro.org
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-v2-1-393caab75cb0@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-v1-1-9e88b908e1b2@linaro.org --- drivers/net/ethernet/xscale/ixp4xx_eth.c | 67 +++++++++++++++++++++++++++++--- 1 file changed, 61 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/xscale/ixp4xx_eth.c b/drivers/net/ethernet/xscale/ixp4xx_eth.c index 8f40287c8d58..910094ab553c 100644 --- a/drivers/net/ethernet/xscale/ixp4xx_eth.c +++ b/drivers/net/ethernet/xscale/ixp4xx_eth.c @@ -64,7 +64,15 @@ #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) #define NAPI_WEIGHT 16 @@ -1183,6 +1191,54 @@ static void destroy_queues(struct port *port) } } +static int ixp4xx_do_change_mtu(struct net_device *dev, int new_mtu) +{ + struct port *port = netdev_priv(dev); + struct npe *npe = port->npe; + int framesize, chunks; + struct msg msg = {}; + + /* adjust for ethernet headers */ + framesize = new_mtu + VLAN_ETH_HLEN; + /* max rx/tx 64 byte chunks */ + chunks = DIV_ROUND_UP(framesize, 64); + + msg.cmd = NPE_SETMAXFRAMELENGTHS; + msg.eth_id = port->id; + + /* Firmware wants to know buffer size in 64 byte chunks */ + msg.byte2 = chunks << 8; + msg.byte3 = chunks << 8; + + msg.byte4 = msg.byte6 = framesize >> 8; + msg.byte5 = msg.byte7 = 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 = ixp4xx_do_change_mtu(dev, new_mtu); + if (ret < 0) + return ret; + } + + dev->mtu = new_mtu; + + return 0; +} + static int eth_open(struct net_device *dev) { struct port *port = netdev_priv(dev); @@ -1233,6 +1289,8 @@ static int eth_open(struct net_device *dev) if (npe_send_recv_message(port->npe, &msg, "ETH_SET_FIREWALL_MODE")) return -EIO; + ixp4xx_do_change_mtu(dev, dev->mtu); + if ((err = request_queues(port)) != 0) return err; @@ -1375,6 +1433,7 @@ static int eth_close(struct net_device *dev) static const struct net_device_ops ixp4xx_netdev_ops = { .ndo_open = eth_open, .ndo_stop = eth_close, + .ndo_change_mtu = ixp4xx_eth_change_mtu, .ndo_start_xmit = eth_xmit, .ndo_set_rx_mode = eth_set_mcast_list, .ndo_eth_ioctl = eth_ioctl, @@ -1489,12 +1548,8 @@ static int ixp4xx_eth_probe(struct platform_device *pdev) ndev->dev.dma_mask = dev->dma_mask; ndev->dev.coherent_dma_mask = dev->coherent_dma_mask; - /* Maximum frame size is 16320 bytes and includes VLAN and - * ethernet headers. See "IXP400 Software Programmer's Guide" - * section 10.3.2, page 161. - */ ndev->min_mtu = ETH_MIN_MTU; - ndev->max_mtu = 16320 - VLAN_ETH_HLEN; + ndev->max_mtu = MAX_MRU; netif_napi_add_weight(ndev, &port->napi, eth_poll, NAPI_WEIGHT); --- base-commit: f22d2ec3d4e72d1f24153533ba0ce8fa926cdd37 change-id: 20230923-ixp4xx-eth-mtu-c041d7efe932 Best regards, -- Linus Walleij <linus.walleij@linaro.org>
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