linux-kernel - [PATCH] i2c: cadence: try reset when master receive arbitration lost

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Message-Id: <20190218094132.5226-1-sxauwsk@163.com>
Date:   Mon, 18 Feb 2019 17:41:32 +0800
From:   Shikai Wang <sxauwsk@....com>
To:     Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>
Cc:     Michal Simek <michal.simek@...inx.com>,
        linux-arm-kernel@...ts.infradead.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, sxauwsk@....com
Subject: [PATCH] i2c: cadence: try reset when master receive arbitration lost

When the adapter receive arbitration lost error interrupts,
cdns_i2c_master_xfer return to the caller directly instead of resetting
the adapter which resulted in the adapter being out of control.

So when driver detect err_status such as arbitration lost,
then try to repair and fix it.

Signed-off-by: Shikai Wang <sxauwsk@....com>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>
---
 drivers/i2c/busses/i2c-cadence.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
index b13605718291..595b0d56ff1a 100644
--- a/drivers/i2c/busses/i2c-cadence.c
+++ b/drivers/i2c/busses/i2c-cadence.c
@@ -548,10 +548,6 @@ static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
 	cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK,
 			  CDNS_I2C_IDR_OFFSET);
 
-	/* If it is bus arbitration error, try again */
-	if (id->err_status & CDNS_I2C_IXR_ARB_LOST)
-		return -EAGAIN;
-
 	return 0;
 }
 
@@ -624,6 +620,12 @@ static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 		if (id->err_status) {
 			cdns_i2c_master_reset(adap);
 
+			/* If it is bus arbitration error, try again */
+			if (id->err_status & CDNS_I2C_IXR_ARB_LOST) {
+				ret = -EAGAIN;
+				goto out;
+			}
+
 			if (id->err_status & CDNS_I2C_IXR_NACK) {
 				ret = -ENXIO;
 				goto out;
-- 
2.19.2