i2c-s3c2410: Enable i2c clock only when doing some transfert

This patch modify the s3c2410 i2c driver behaviour to enable the
i2c clock only when needed. I'm not sure if this has a big impact
on power usage but at least it's fixing a bug with the uda1380
codec which needs to be hard reset'ed if the i2c clock is enabled
before it's powered on (at least on h1940).

Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index bf831bf81587..3dc1eb9f8088 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -555,18 +555,23 @@ static int s3c24xx_i2c_xfer(struct i2c_adapter *adap,
         int retry;
         int ret;
 
+        clk_enable(i2c->clk);
+
         for (retry = 0; retry < adap->retries; retry++) {
 
                 ret = s3c24xx_i2c_doxfer(i2c, msgs, num);
 
-                if (ret != -EAGAIN)
+                if (ret != -EAGAIN) {
+                        clk_disable(i2c->clk);
                         return ret;
+                }
 
                 dev_dbg(i2c->dev, "Retrying transmission (%d)\n", retry);
 
                 udelay(100);
         }
 
+        clk_disable(i2c->clk);
         return -EREMOTEIO;
 }
 
@@ -911,6 +916,7 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev)
         platform_set_drvdata(pdev, i2c);
 
         dev_info(&pdev->dev, "%s: S3C I2C adapter\n", dev_name(&i2c->adap.dev));
+        clk_disable(i2c->clk);
         return 0;
 
  err_cpufreq:
@@ -978,7 +984,9 @@ static int s3c24xx_i2c_resume(struct device *dev)
         struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
 
         i2c->suspended = 0;
+        clk_enable(i2c->clk);
         s3c24xx_i2c_init(i2c);
+        clk_disable(i2c->clk);
 
         return 0;
 }