serial: clear proper MPSC interrupt cause bits

The interrupt clearing code in mpsc_sdma_intr_ack() mistakenly clears the
interrupt for both controllers instead of just the one its supposed to.
This can result in the other controller appearing to hang because its
interrupt was effectively lost.

So, don't clear the interrupt cause bits for both MPSC controllers when
clearing the interrupt for one of them.  Just clear the one that is
supposed to be cleared.

Signed-off-by: Jay Lubomirski <jaylubo@motorola.com>
Acked-by: Mark A. Greer <mgreer@mvista.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/serial/mpsc.c b/drivers/serial/mpsc.c
index d09f2097d5b0ce6abc9cd25f849e19d37a3b0064..00924feaf621831caa46267ad8b9b278a48a8552 100644 (file)
--- a/drivers/serial/mpsc.c
+++ b/drivers/serial/mpsc.c
@@ -503,7 +503,8 @@ mpsc_sdma_intr_ack(struct mpsc_port_info *pi)
 
        if (pi->mirror_regs)
                pi->shared_regs->SDMA_INTR_CAUSE_m = 0;
-       writel(0, pi->shared_regs->sdma_intr_base + SDMA_INTR_CAUSE);
+       writeb(0x00, pi->shared_regs->sdma_intr_base + SDMA_INTR_CAUSE +
+              pi->port.line);
        return;
 }