2011/11/2 Russell King - ARM Linux [off-list ref]:

On Wed, Nov 02, 2011 at 10:39:04AM +0000, Jamie Iles wrote:

quoted

quoted

+ ? clk = clk_get(&pdev->dev, NULL);
+ ? if (IS_ERR(clk)) {
+ ? ? ? ? ? err = PTR_ERR(clk);
+ ? ? ? ? ? dev_err(&pdev->dev, "Clock get failed\n");
+ ? ? ? ? ? goto out;
+ ? }
+
+ ? clk_enable(clk);

The return value of clk_enable() should really be checked.

Now that the clk_prepare() patch has been enabled, new drivers should be
written assuming that clk_prepare() will be necessary before clk_enable().

And one may query why it's not possible to use clk_enable()...clk_disable()
around the transfer itself, so the clock can be turned off while the device
is idle. ?Obviously if its expecting to be operated in slave mode as well
then you may need to keep the clock enabled.

yes. we can have a clk_enable at the beginning of i2c_sirfsoc_xfer and
clk_disable at the end.
i need some tests to check the hardware is robust enough.
actually, i can add runtime pm as well.

-barry