On Thu, 2014-06-12 at 05:50PM +0900, Jongsung Kim wrote:
> The "Rx used bit read" interrupt is enabled but not cleared for some
> systems with the ISR (Interrupt Status Register) configured as clear-
> on-write. This interrupt may be asserted when the CPU does not handle
> Rx-complete interrupts for a long time. (e.g., if the CPU is stopped
> by debugger) Once asserted, it'll not be cleared, and the CPU will
> loop infinitly in the interrupt handler.
>
> This patch forces to use a dedicated function for reading the ISR,
> and the function clears it if clear-on-write. So the ISR is always
> cleared after read, regardless of clear-on-write configuration.
>
> Reported-by: Hayun Hwang <hwang.ha...@lge.com>
> Signed-off-by: Youngkyu Choi <youngkyu7.c...@lge.com>
> Signed-off-by: Jongsung Kim <neidhard....@lge.com>
> Tested-by: Hayun Hwang <hwang.ha...@lge.com>
> ---
> drivers/net/ethernet/cadence/macb.c | 37 ++++++++++++++--------------------
> 1 files changed, 15 insertions(+), 22 deletions(-)
>
[...]
> @@ -552,9 +562,6 @@ static void macb_tx_interrupt(struct macb *bp)
> status = macb_readl(bp, TSR);
> macb_writel(bp, TSR, status);
>
> - if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
> - macb_writel(bp, ISR, MACB_BIT(TCOMP));
> -
> netdev_vdbg(bp->dev, "macb_tx_interrupt status = 0x%03lx\n",
> (unsigned long)status);
>
> @@ -883,13 +890,10 @@ static int macb_poll(struct napi_struct *napi, int
> budget)
>
> /* Packets received while interrupts were disabled */
> status = macb_readl(bp, RSR);
> - if (status) {
> - if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
> - macb_writel(bp, ISR, MACB_BIT(RCOMP));
> + if (status)
> napi_reschedule(napi);
> - } else {
> + else
> macb_writel(bp, IER, MACB_RX_INT_FLAGS);
> - }
> }
>
> /* TODO: Handle errors */
> @@ -903,7 +907,7 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
> struct macb *bp = netdev_priv(dev);
> u32 status;
>
> - status = macb_readl(bp, ISR);
> + status = macb_read_isr(bp);
>
> if (unlikely(!status))
> return IRQ_NONE;
> @@ -928,8 +932,6 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
> * now.
> */
> macb_writel(bp, IDR, MACB_RX_INT_FLAGS);
> - if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
> - macb_writel(bp, ISR, MACB_BIT(RCOMP));
Shouldn't it be sufficient to replace 'MACB_BIT(RCOMP) with 'MACB_RX_INT_FLAGS'
to clear all the RX IRQ flags.
Sören
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