From dd318b0df27c582ac0d72a346fd6e693700be23c Mon Sep 17 00:00:00 2001
From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Date: Tue, 2 Sep 2014 01:15:26 +0400
Subject: [PATCH] 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>
---
drivers/i2c/busses/i2c-rcar.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index f3c7139dfa251f..dc32f5fa75d019 100644
--- 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
--
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