1 files changed, 27 insertions, 16 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 85e2e919d1cd..5ed622ee65c3 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -29,7 +29,6 @@
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/idr.h>
-#include <linux/platform_device.h>
 #include <linux/mutex.h>
 #include <linux/completion.h>
 #include <linux/hardirq.h>
@@ -451,16 +450,6 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 
         mutex_lock(&core_lock);
 
-        /* Add the adapter to the driver core.
-         * If the parent pointer is not set up,
-         * we add this adapter to the host bus.
-         */
-        if (adap->dev.parent == NULL) {
-                adap->dev.parent = &platform_bus;
-                pr_debug("I2C adapter driver [%s] forgot to specify "
-                         "physical device\n", adap->name);
-        }
-
         /* Set default timeout to 1 second if not already set */
         if (adap->timeout == 0)
                 adap->timeout = HZ;
@@ -1022,7 +1011,8 @@ module_exit(i2c_exit);
  */
 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 {
-        int ret;
+        unsigned long orig_jiffies;
+        int ret, try;
 
         /* REVISIT the fault reporting model here is weak:
          *
@@ -1060,7 +1050,15 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
                         mutex_lock_nested(&adap->bus_lock, adap->level);
                 }
 
-                ret = adap->algo->master_xfer(adap,msgs,num);
+                /* Retry automatically on arbitration loss */
+                orig_jiffies = jiffies;
+                for (ret = 0, try = 0; try <= adap->retries; try++) {
+                        ret = adap->algo->master_xfer(adap, msgs, num);
+                        if (ret != -EAGAIN)
+                                break;
+                        if (time_after(jiffies, orig_jiffies + adap->timeout))
+                                break;
+                }
                 mutex_unlock(&adap->bus_lock);
 
                 return ret;
@@ -1509,7 +1507,7 @@ struct i2c_adapter* i2c_get_adapter(int id)
         struct i2c_adapter *adapter;
 
         mutex_lock(&core_lock);
-        adapter = (struct i2c_adapter *)idr_find(&i2c_adapter_idr, id);
+        adapter = idr_find(&i2c_adapter_idr, id);
         if (adapter && !try_module_get(adapter->owner))
                 adapter = NULL;
 
@@ -1995,14 +1993,27 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
                    char read_write, u8 command, int protocol,
                    union i2c_smbus_data *data)
 {
+        unsigned long orig_jiffies;
+        int try;
         s32 res;
 
         flags &= I2C_M_TEN | I2C_CLIENT_PEC;
 
         if (adapter->algo->smbus_xfer) {
                 mutex_lock(&adapter->bus_lock);
-                res = adapter->algo->smbus_xfer(adapter,addr,flags,read_write,
-                                                command, protocol, data);
+
+                /* Retry automatically on arbitration loss */
+                orig_jiffies = jiffies;
+                for (res = 0, try = 0; try <= adapter->retries; try++) {
+                        res = adapter->algo->smbus_xfer(adapter, addr, flags,
+                                                        read_write, command,
+                                                        protocol, data);
+                        if (res != -EAGAIN)
+                                break;
+                        if (time_after(jiffies,
+                                       orig_jiffies + adapter->timeout))
+                                break;
+                }
                 mutex_unlock(&adapter->bus_lock);
         } else
                 res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write,