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Date:   Thu, 23 Nov 2017 11:42:36 +0000
From:   "Zhang, Sean C. (NSB - CN/Hangzhou)" <sean.c.zhang@...ia-sbell.com>
To:     "jglauber@...ium.com" <jglauber@...ium.com>,
        "david.daney@...ium.com" <david.daney@...ium.com>,
        "wsa@...-dreams.de" <wsa@...-dreams.de>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [Bug fix] octeon-i2c driver updates

Dear Maintainer,

For octeon TWSI controller, I found below two cases, maybe can be improved.


>From 09d9f0ce658d7f6a50d1af352dde619c29bc8bcf Mon Sep 17 00:00:00 2001
From: hgt463 <sean.c.zhang@...ia.com>
Date: Thu, 23 Nov 2017 18:46:09 +0800
Subject: [PATCH] Driver updates:
 - In the case of I2C bus dead lock occurred during driver probing,
   it is better try to recovery it. so added bus recovery step in
   octeon_i2c_probe();
 - The purpose of function octeon_i2c_start() is to send START, so after
   bus recovery, also need try to send START again.

Signed-off-by: hgt463 <sean.c.zhang@...ia.com>
---
 drivers/i2c/busses/i2c-octeon-core.c    |   31 ++++++++++++++++++++++++++++++-
 drivers/i2c/busses/i2c-octeon-platdrv.c |   15 +++++++++------
 2 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-octeon-core.c b/drivers/i2c/busses/i2c-octeon-core.c
index 1d87757..3ae1e03 100644
--- a/drivers/i2c/busses/i2c-octeon-core.c
+++ b/drivers/i2c/busses/i2c-octeon-core.c
@@ -255,6 +255,35 @@ static int octeon_i2c_recovery(struct octeon_i2c *i2c)
        return ret;
 }
 
+/*
+ * octeon_i2c_start_retry - send START to the bus after bus recovery.
+ * @i2c: The struct octeon_i2c
+ *
+ * Returns 0 on success, otherwise a negative errno.
+ */
+static int octeon_i2c_start_retry(struct octeon_i2c *i2c)
+{
+       int ret;
+       u8 stat;
+
+       ret = octeon_i2c_recovery(i2c);
+       if (ret)
+               goto error;
+
+       octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB | TWSI_CTL_STA);
+       ret = octeon_i2c_wait(i2c);
+       if (ret)
+               goto error;
+
+       stat = octeon_i2c_stat_read(i2c);
+       if (stat == STAT_START || stat == STAT_REP_START)
+               /* START successful, bail out */
+               return 0;
+
+error:
+       return (ret) ? ret : -EAGAIN;
+}
+
 /**
  * octeon_i2c_start - send START to the bus
  * @i2c: The struct octeon_i2c
@@ -280,7 +309,7 @@ static int octeon_i2c_start(struct octeon_i2c *i2c)
 
 error:
        /* START failed, try to recover */
-       ret = octeon_i2c_recovery(i2c);
+       ret = octeon_i2c_start_retry(i2c);
        return (ret) ? ret : -EAGAIN;
 }
 
diff --git a/drivers/i2c/busses/i2c-octeon-platdrv.c b/drivers/i2c/busses/i2c-octeon-platdrv.c
index 64bda83..98063af 100644
--- a/drivers/i2c/busses/i2c-octeon-platdrv.c
+++ b/drivers/i2c/busses/i2c-octeon-platdrv.c
@@ -228,12 +228,6 @@ static int octeon_i2c_probe(struct platform_device *pdev)
        if (OCTEON_IS_MODEL(OCTEON_CN38XX))
                i2c->broken_irq_check = true;
 
-       result = octeon_i2c_init_lowlevel(i2c);
-       if (result) {
-               dev_err(i2c->dev, "init low level failed\n");
-               goto  out;
-       }
-
        octeon_i2c_set_clock(i2c);
 
        i2c->adap = octeon_i2c_ops;
@@ -245,6 +239,15 @@ static int octeon_i2c_probe(struct platform_device *pdev)
        i2c_set_adapdata(&i2c->adap, i2c);
        platform_set_drvdata(pdev, i2c);
 
+       stat = octeon_i2c_stat_read(i2c);
+       if (stat != STAT_IDLE) {
+               result = octeon_i2c_recovery(i2c);
+               if (result) {
+                       dev_err(i2c->dev, "octeon i2c recovery failed\n");
+                       goto  out;
+               }
+       }
+
        result = i2c_add_adapter(&i2c->adap);
        if (result < 0)
                goto out;


Attached patch for you review. Thanks in advance.

BR,
Sean Zhang

Download attachment "0001-Driver-updates.patch" of type "application/octet-stream" (2929 bytes)

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