[PATCH] ppc32: workaround for spurious IRQs on PQ2

There is a problem with large amounts of spurious IRQs on PowerPC 82xx
systems.

The problem is corrected by adding sync at the end of cpm2_mask_and_ack.
This may be needed on 8xx as well but has not yet been confirmed.

Signed-off-by: Eugene Surovegin <ebs@ebshome.net>
Signed-off-by: Dan Malek <dan@embeddedalley.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/ppc/syslib/cpm2_pic.c b/arch/ppc/syslib/cpm2_pic.c
index 954b07fc1df3..c867be6981cb 100644
--- a/arch/ppc/syslib/cpm2_pic.c
+++ b/arch/ppc/syslib/cpm2_pic.c
@@ -107,6 +107,11 @@ static void cpm2_end_irq(unsigned int irq_nr)
                 simr = &(cpm2_immr->im_intctl.ic_simrh);
                 ppc_cached_irq_mask[word] |= 1 << bit;
                 simr[word] = ppc_cached_irq_mask[word];
+                /*
+                 * Work around large numbers of spurious IRQs on PowerPC 82xx
+                 * systems.
+                 */
+                mb();
         }
 }