The controller specification states that when receiving STAT_RXADDR_NAK
the START should be sent again. Retry several times before finally
failing with -ENXIO.

Without this change the IPMI SSIF driver fails executing several commands
like 'ipmitool fru' on ThunderX.

Signed-off-by: Jan Glauber <jglau...@cavium.com>
---
 drivers/i2c/busses/i2c-octeon.c | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-octeon.c b/drivers/i2c/busses/i2c-octeon.c
index 1922e4a..8ade7fb 100644
--- a/drivers/i2c/busses/i2c-octeon.c
+++ b/drivers/i2c/busses/i2c-octeon.c
@@ -880,6 +880,10 @@ static int octeon_i2c_write(struct octeon_i2c *i2c, int 
target,
 {
        int i, result;
 
+       result = octeon_i2c_start(i2c);
+       if (result)
+               return result;
+
        octeon_i2c_data_write(i2c, target << 1);
        octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
 
@@ -918,9 +922,14 @@ static int octeon_i2c_write(struct octeon_i2c *i2c, int 
target,
 static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
                           u8 *data, u16 *rlength, bool recv_len)
 {
-       int i, result, length = *rlength;
+       int i, result, length = *rlength, retries = 10;
        bool final_read = false;
 
+restart:
+       result = octeon_i2c_start(i2c);
+       if (result)
+               return result;
+
        octeon_i2c_data_write(i2c, (target << 1) | 1);
        octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
 
@@ -930,8 +939,17 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int 
target,
 
        /* address OK ? */
        result = octeon_i2c_check_status(i2c, false);
-       if (result)
-               return result;
+       if (result) {
+               /*
+                * According to controller specification on STAT_RXADDR_NAK
+                * the START should be repeated so retry several times before
+                * giving up with -ENXIO.
+                */
+               if (result == -ENXIO && --retries > 0)
+                       goto restart;
+               else
+                       return result;
+       }
 
        for (i = 0; i < length; i++) {
                /*
@@ -1019,10 +1037,6 @@ static int octeon_i2c_xfer(struct i2c_adapter *adap, 
struct i2c_msg *msgs,
                        break;
                }
 
-               ret = octeon_i2c_start(i2c);
-               if (ret)
-                       return ret;
-
                if (pmsg->flags & I2C_M_RD)
                        ret = octeon_i2c_read(i2c, pmsg->addr, pmsg->buf,
                                              &pmsg->len, pmsg->flags & 
I2C_M_RECV_LEN);
-- 
2.9.0.rc0.21.g7777322

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