i2c: designware: Prevent runtime suspend during adapter registration

[deliverable/linux.git] / drivers / i2c / busses / i2c-designware-core.c

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 10fbd6d841e06aef8ae0a627f9fcf36106f5119b..99b54be6ba73f814579b50f51936b09effafc25d 100644 (file)
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -634,7 +634,6 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 
        dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);
 
-       mutex_lock(&dev->lock);
        pm_runtime_get_sync(dev->dev);
 
        reinit_completion(&dev->cmd_complete);
@@ -673,11 +672,12 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
        }
 
        /*
-        * We must disable the adapter before unlocking the &dev->lock mutex
-        * below. Otherwise the hardware might continue generating interrupts
-        * which in turn causes a race condition with the following transfer.
-        * Needs some more investigation if the additional interrupts are
-        * a hardware bug or this driver doesn't handle them correctly yet.
+        * We must disable the adapter before returning and signaling the end
+        * of the current transfer. Otherwise the hardware might continue
+        * generating interrupts which in turn causes a race condition with
+        * the following transfer.  Needs some more investigation if the
+        * additional interrupts are a hardware bug or this driver doesn't
+        * handle them correctly yet.
         */
        __i2c_dw_enable(dev, false);
 
@@ -706,7 +706,6 @@ done:
 done_nolock:
        pm_runtime_mark_last_busy(dev->dev);
        pm_runtime_put_autosuspend(dev->dev);
-       mutex_unlock(&dev->lock);
 
        return ret;
 }
@@ -860,7 +859,6 @@ int i2c_dw_probe(struct dw_i2c_dev *dev)
        int r;
 
        init_completion(&dev->cmd_complete);
-       mutex_init(&dev->lock);
 
        r = i2c_dw_init(dev);
        if (r)
@@ -883,9 +881,17 @@ int i2c_dw_probe(struct dw_i2c_dev *dev)
                return r;
        }
 
+       /*
+        * Increment PM usage count during adapter registration in order to
+        * avoid possible spurious runtime suspend when adapter device is
+        * registered to the device core and immediate resume in case bus has
+        * registered I2C slaves that do I2C transfers in their probe.
+        */
+       pm_runtime_get_noresume(dev->dev);
        r = i2c_add_numbered_adapter(adap);
        if (r)
                dev_err(dev->dev, "failure adding adapter: %d\n", r);
+       pm_runtime_put_noidle(dev->dev);
 
        return r;
 }