[PATCH net-next v1 4/5] net: lan743x: reset the device on TX timeout
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HOTtoday
From: Chris Babroski <hidden>
Date: 2026-10-15 15:02:55
Also in:
lkml
Subsystem:
microchip lan743x ethernet driver, networking drivers, the rest · Maintainers:
Bryan Whitehead, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The driver does not implement ndo_tx_timeout, so the core TX watchdog is never started. If a TX DMA channel stops completing descriptors, its queue stays stopped and the interface cannot transmit again until it is brought down and back up. Add an ndo_tx_timeout handler that schedules a work item to reset the device. Under rtnl_lock(), the work detaches the netdev, closes it, soft-resets the DMA controller, opens it again and reattaches it. This is the sequence suspend and resume already use, with the DMA controller reset taking the place of the full hardware init. Because everything is reopened, the RX path, PTP and the PHY link are restarted along with TX. For PTP, the reset has the same effect as bringing the interface down and up. As on suspend and resume, the PTP clock is unregistered and registered again, and its time is reset to the system time. The hardware timestamping state is also reset, so the RX filter returns to none and one-step sync insertion is disabled, while the driver keeps its TX timestamping flags. PTP applications have to set up timestamping again. lan743x_dmac_init() did not check that the DMA controller soft reset completed, so the work could reopen a controller whose reset timed out. Return the error from the poll so the work can tell. Probe already fails when lan743x_dmac_init() returns an error, so a controller that does not come out of reset now also fails probe. If lan743x_dmac_init() or the reopen returns an error, the interface is taken down with dev_close() so it can be brought back up later. The hardware is already closed at that point, so route ndo_stop through a wrapper that skips the hardware close while the device is detached. ndo_stop is called with rtnl held and cannot wait for the work, so it only cancels a pending one. A work that is already waiting for rtnl returns if the device is still down when it gets the lock. If the device was opened again in the meantime, it is reset once more, which only costs an extra link flap. On remove, the work is cancelled synchronously after the netdev is unregistered. Assisted-by: LLM Signed-off-by: Chris Babroski <redacted> --- drivers/net/ethernet/microchip/lan743x_main.c | 74 ++++++++++++++++++- drivers/net/ethernet/microchip/lan743x_main.h | 2 + 2 files changed, 73 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index 8d256a80dac6..2545a846478d 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c@@ -1516,10 +1516,14 @@ static void lan743x_rfe_set_multicast(struct lan743x_adapter *adapter) static int lan743x_dmac_init(struct lan743x_adapter *adapter) { u32 data = 0; + int ret; lan743x_csr_write(adapter, DMAC_CMD, DMAC_CMD_SWR_); - lan743x_csr_wait_for_bit(adapter, DMAC_CMD, DMAC_CMD_SWR_, - 0, 1000, 20000, 100); + ret = lan743x_csr_wait_for_bit(adapter, DMAC_CMD, DMAC_CMD_SWR_, + 0, 1000, 20000, 100); + if (ret) + return ret; + switch (DEFAULT_DMA_DESCRIPTOR_SPACING) { case DMA_DESCRIPTOR_SPACING_16: data = DMAC_CFG_MAX_DSPACE_16_;
@@ -3335,6 +3339,12 @@ static int lan743x_netdev_close(struct net_device *netdev) struct lan743x_adapter *adapter = netdev_priv(netdev); int index; + /* lan743x_reset_work() takes rtnl, so it cannot be waited for here. + * A running one returns if the device is still down when it gets + * rtnl, otherwise it resets the reopened device once more. + */ + cancel_work(&adapter->reset_work); + lan743x_phylink_disconnect(adapter); synchronize_net();
@@ -3431,6 +3441,61 @@ static int lan743x_netdev_open(struct net_device *netdev) return ret; } +static int lan743x_netdev_stop(struct net_device *netdev) +{ + if (!netif_device_present(netdev)) + return 0; + + return lan743x_netdev_close(netdev); +} + +static void lan743x_reset_work(struct work_struct *work) +{ + struct lan743x_adapter *adapter = + container_of(work, struct lan743x_adapter, reset_work); + struct net_device *netdev = adapter->netdev; + int ret; + + rtnl_lock(); + + if (!netif_running(netdev) || !netif_device_present(netdev)) + goto unlock; + + netdev_warn(netdev, "resetting after TX timeout\n"); + + netif_device_detach(netdev); + lan743x_netdev_close(netdev); + + ret = lan743x_dmac_init(adapter); + if (ret) { + netdev_err(netdev, "DMA controller reset failed: %d\n", ret); + goto close; + } + + ret = lan743x_netdev_open(netdev); + if (ret) { + netdev_err(netdev, "failed to reopen after reset: %d\n", ret); + goto close; + } + + goto attach; + +close: + dev_close(netdev); +attach: + netif_device_attach(netdev); +unlock: + rtnl_unlock(); +} + +static void lan743x_netdev_tx_timeout(struct net_device *netdev, + unsigned int txqueue) +{ + struct lan743x_adapter *adapter = netdev_priv(netdev); + + schedule_work(&adapter->reset_work); +} + static netdev_tx_t lan743x_netdev_xmit_frame(struct sk_buff *skb, struct net_device *netdev) {
@@ -3537,8 +3602,9 @@ static int lan743x_netdev_set_mac_address(struct net_device *netdev, static const struct net_device_ops lan743x_netdev_ops = { .ndo_open = lan743x_netdev_open, - .ndo_stop = lan743x_netdev_close, + .ndo_stop = lan743x_netdev_stop, .ndo_start_xmit = lan743x_netdev_xmit_frame, + .ndo_tx_timeout = lan743x_netdev_tx_timeout, .ndo_eth_ioctl = lan743x_netdev_ioctl, .ndo_set_rx_mode = lan743x_netdev_set_multicast, .ndo_change_mtu = lan743x_netdev_change_mtu,
@@ -3567,6 +3633,7 @@ static void lan743x_destroy_phylink(struct lan743x_adapter *adapter) static void lan743x_full_cleanup(struct lan743x_adapter *adapter) { unregister_netdev(adapter->netdev); + cancel_work_sync(&adapter->reset_work); lan743x_destroy_phylink(adapter); lan743x_mdiobus_cleanup(adapter);
@@ -3761,6 +3828,7 @@ static int lan743x_pcidev_probe(struct pci_dev *pdev, NETIF_MSG_LINK | NETIF_MSG_IFUP | NETIF_MSG_IFDOWN | NETIF_MSG_TX_QUEUED; netdev->max_mtu = LAN743X_MAX_FRAME_SIZE; + INIT_WORK(&adapter->reset_work, lan743x_reset_work); of_get_mac_address(pdev->dev.of_node, adapter->mac_address);
diff --git a/drivers/net/ethernet/microchip/lan743x_main.h b/drivers/net/ethernet/microchip/lan743x_main.h
index d9495cf96b41..2697f0a2a83b 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.h
+++ b/drivers/net/ethernet/microchip/lan743x_main.h@@ -6,6 +6,7 @@ #include <linux/phy.h> #include <linux/phylink.h> +#include <linux/workqueue.h> #include "lan743x_ptp.h" #define DRIVER_AUTHOR "Bryan Whitehead <Bryan.Whitehead@microchip.com>"
@@ -1075,6 +1076,7 @@ struct lan743x_adapter { struct lan743x_phy phy; struct lan743x_tx tx[PCI11X1X_USED_TX_CHANNELS]; struct lan743x_rx rx[LAN743X_USED_RX_CHANNELS]; + struct work_struct reset_work; bool is_pci11x1x; bool is_sgmii_en; bool is_rmii_en;
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2.34.1