i2c: davinci: fix the cpufreq transition

i2c_davinci_cpufreq_transition() is implemented in a way that will
block if it ever gets called while no transfer is in progress.

Not only that, but reinit_completion() is never called for xfr_complete.

Use the fact that cpufreq uses an srcu_notifier (running in process
context) for transitions and that the bus_lock is taken during the call
to master_xfer() and simplify the code by removing the transfer
completion entirely and protecting i2c_davinci_cpufreq_transition()
with i2c_lock/unlock_adapter().

Reported-by: David Lechner <david@lechnology.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Sekhar Nori <nsekhar@ti.com>
Tested-by: David Lechner <david@lechnology.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index cb24a3ffdfa2739b754048caa0972f57c33d9e2f..75d6ab177055efa2119635eb56845388ac3a0848 100644 (file)
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -139,7 +139,6 @@ struct davinci_i2c_dev {
        u8                      terminate;
        struct i2c_adapter      adapter;
 #ifdef CONFIG_CPU_FREQ
-       struct completion       xfr_complete;
        struct notifier_block   freq_transition;
 #endif
        struct davinci_i2c_platform_data *pdata;
@@ -567,9 +566,6 @@ i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
        }
 
        ret = num;
-#ifdef CONFIG_CPU_FREQ
-       complete(&dev->xfr_complete);
-#endif
 
 out:
        pm_runtime_mark_last_busy(dev->dev);
@@ -717,13 +713,15 @@ static int i2c_davinci_cpufreq_transition(struct notifier_block *nb,
        struct davinci_i2c_dev *dev;
 
        dev = container_of(nb, struct davinci_i2c_dev, freq_transition);
+
+       i2c_lock_adapter(&dev->adapter);
        if (val == CPUFREQ_PRECHANGE) {
-               wait_for_completion(&dev->xfr_complete);
                davinci_i2c_reset_ctrl(dev, 0);
        } else if (val == CPUFREQ_POSTCHANGE) {
                i2c_davinci_calc_clk_dividers(dev);
                davinci_i2c_reset_ctrl(dev, 1);
        }
+       i2c_unlock_adapter(&dev->adapter);
 
        return 0;
 }
@@ -790,9 +788,7 @@ static int davinci_i2c_probe(struct platform_device *pdev)
        }
 
        init_completion(&dev->cmd_complete);
-#ifdef CONFIG_CPU_FREQ
-       init_completion(&dev->xfr_complete);
-#endif
+
        dev->dev = &pdev->dev;
        dev->irq = irq;
        dev->pdata = dev_get_platdata(&pdev->dev);