From 686f85d71d095f1d26b807e23b0f0bfd22042c45 Mon Sep 17 00:00:00 2001 From: Finn Thain Date: Thu, 23 Jan 2020 09:07:26 +1100 Subject: net/sonic: Prevent tx watchdog timeout Section 5.5.3.2 of the datasheet says, If FIFO Underrun, Byte Count Mismatch, Excessive Collision, or Excessive Deferral (if enabled) errors occur, transmission ceases. In this situation, the chip asserts a TXER interrupt rather than TXDN. But the handler for the TXDN is the only way that the transmit queue gets restarted. Hence, an aborted transmission can result in a watchdog timeout. This problem can be reproduced on congested link, as that can result in excessive transmitter collisions. Another way to reproduce this is with a FIFO Underrun, which may be caused by DMA latency. In event of a TXER interrupt, prevent a watchdog timeout by restarting transmission. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Tested-by: Stan Johnson Signed-off-by: Finn Thain Signed-off-by: David S. Miller --- drivers/net/ethernet/natsemi/sonic.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) (limited to 'drivers/net/ethernet') diff --git a/drivers/net/ethernet/natsemi/sonic.c b/drivers/net/ethernet/natsemi/sonic.c index 27b6f6585527..05e760444a92 100644 --- a/drivers/net/ethernet/natsemi/sonic.c +++ b/drivers/net/ethernet/natsemi/sonic.c @@ -415,10 +415,19 @@ static irqreturn_t sonic_interrupt(int irq, void *dev_id) lp->stats.rx_missed_errors += 65536; /* transmit error */ - if (status & SONIC_INT_TXER) - if (SONIC_READ(SONIC_TCR) & SONIC_TCR_FU) - netif_dbg(lp, tx_err, dev, "%s: tx fifo underrun\n", - __func__); + if (status & SONIC_INT_TXER) { + u16 tcr = SONIC_READ(SONIC_TCR); + + netif_dbg(lp, tx_err, dev, "%s: TXER intr, TCR %04x\n", + __func__, tcr); + + if (tcr & (SONIC_TCR_EXD | SONIC_TCR_EXC | + SONIC_TCR_FU | SONIC_TCR_BCM)) { + /* Aborted transmission. Try again. */ + netif_stop_queue(dev); + SONIC_WRITE(SONIC_CMD, SONIC_CR_TXP); + } + } /* bus retry */ if (status & SONIC_INT_BR) { -- cgit