i2c: rcar: fix MNR interrupt handling

Sometimes the MNR and MST interrupts happen simultaneously  (stop  automatically
follows NACK, according to the manuals) and in such case the ID_NACK flag  isn't
set since the MST interrupt handling precedes MNR and all interrupts are cleared
and disabled then, so that MNR interrupt is never noticed -- this causes NACK'ed
transfers to be falsely reported as successful. Exchanging MNR and  MST handlers
fixes this issue, however the MNR bit  somehow  gets set again even after  being
explicitly cleared, so I decided to completely suppress handling of all disabled
interrupts (which is a good thing anyway)...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: stable@vger.kernel.org
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index f3c7139dfa251f51b6c67da1b9f2de869fb6860d..dc32f5fa75d019dc52c2601dd4cbcab5ba6d5e86 100644 (file)
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -367,18 +367,15 @@ static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
 
        msr = rcar_i2c_read(priv, ICMSR);
 
+       /* Only handle interrupts that are currently enabled */
+       msr &= rcar_i2c_read(priv, ICMIER);
+
        /* Arbitration lost */
        if (msr & MAL) {
                rcar_i2c_flags_set(priv, (ID_DONE | ID_ARBLOST));
                goto out;
        }
 
-       /* Stop */
-       if (msr & MST) {
-               rcar_i2c_flags_set(priv, ID_DONE);
-               goto out;
-       }
-
        /* Nack */
        if (msr & MNR) {
                /* go to stop phase */
@@ -388,6 +385,12 @@ static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
                goto out;
        }
 
+       /* Stop */
+       if (msr & MST) {
+               rcar_i2c_flags_set(priv, ID_DONE);
+               goto out;
+       }
+
        if (rcar_i2c_is_recv(priv))
                rcar_i2c_flags_set(priv, rcar_i2c_irq_recv(priv, msr));
        else