net/sonic: Prevent tx watchdog timeout
commit5.4-rM2-2.2.x-imx-squashed686f85d71d
upstream. 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:1da177e4c3
("Linux-2.6.12-rc2") Tested-by: Stan Johnson <userm57@yahoo.com> Signed-off-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
parent
58c0c4b122
commit
74389183b6
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@ -415,10 +415,19 @@ static irqreturn_t sonic_interrupt(int irq, void *dev_id)
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lp->stats.rx_missed_errors += 65536;
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/* transmit error */
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if (status & SONIC_INT_TXER)
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if (SONIC_READ(SONIC_TCR) & SONIC_TCR_FU)
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netif_dbg(lp, tx_err, dev, "%s: tx fifo underrun\n",
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__func__);
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if (status & SONIC_INT_TXER) {
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u16 tcr = SONIC_READ(SONIC_TCR);
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netif_dbg(lp, tx_err, dev, "%s: TXER intr, TCR %04x\n",
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__func__, tcr);
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if (tcr & (SONIC_TCR_EXD | SONIC_TCR_EXC |
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SONIC_TCR_FU | SONIC_TCR_BCM)) {
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/* Aborted transmission. Try again. */
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netif_stop_queue(dev);
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SONIC_WRITE(SONIC_CMD, SONIC_CR_TXP);
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}
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}
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/* bus retry */
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if (status & SONIC_INT_BR) {
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