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net: macb: ensure ordering write to re-enable RX smoothly

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When a hardware issue happened as described by inline comments, the register
write pattern looks like the following:

<write ~MACB_BIT(RE)>
+ wmb();
<write MACB_BIT(RE)>

There might be a memory barrier between these two write operations, so add wmb
to ensure an flip from 0 to 1 for NCR.

Signed-off-by: Zumeng Chen <zumeng.chen@windriver.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Zumeng Chen 2016-11-28 21:55:00 +08:00 committed by David S. Miller
parent a0b44eea37
commit ffac0e967f
1 changed files with 2 additions and 0 deletions
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2
drivers/net/ethernet/cadence/macb.c
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@ -1157,6 +1157,7 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
if (status & MACB_BIT(RXUBR)) {
ctrl = macb_readl(bp, NCR);
macb_writel(bp, NCR, ctrl & ~MACB_BIT(RE));
wmb();
macb_writel(bp, NCR, ctrl | MACB_BIT(RE));
if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
@ -2769,6 +2770,7 @@ static irqreturn_t at91ether_interrupt(int irq, void *dev_id)
if (intstatus & MACB_BIT(RXUBR)) {
ctl = macb_readl(lp, NCR);
macb_writel(lp, NCR, ctl & ~MACB_BIT(RE));
wmb();
macb_writel(lp, NCR, ctl | MACB_BIT(RE));
}