i2c-s3c2410: Enable i2c clock only when doing some transfert
Arnaud Patard (Rtp) [Thu, 15 Jul 2010 13:06:14 +0000 (15:06 +0200)]
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>

drivers/i2c/busses/i2c-s3c2410.c

index bf831bf..3dc1eb9 100644 (file)
@@ -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;
 }