[PATCH] I2C: add CSR SiRFprimaII on-chip I2C controllers driver

[Barry Song]

2011/11/2 Russell King - ARM Linux <linux at arm.linux.org.uk>:
> On Wed, Nov 02, 2011 at 10:39:04AM +0000, Jamie Iles wrote:
>> > +   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