[PATCH 4/4] i2c: imx: disable clock when it's possible to save power.

[Richard Zhao]

On Thu, Oct 1, 2009 at 4:00 PM, Sascha Hauer <s.hauer at pengutronix.de> wrote:
> On Thu, Oct 01, 2009 at 03:56:29PM +0800, Richard Zhao wrote:
>> On Thu, Oct 1, 2009 at 3:34 PM, Sascha Hauer <s.hauer at pengutronix.de> wrote:
>> > On Thu, Oct 01, 2009 at 09:13:33AM +0800, Richard Zhao wrote:
>> >> Enable clock before START, disable it after STOP.
>> >
>> > The clk_diable/enable calls in suspend/resume should be removed also.
>> >
>> > Sascha
>> >
>> >>
>> >> Signed-off-by: Richard Zhao <linuxzsc at gmail.com>
>> >>
>> >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
>> >> index 87faea4..72ddea3 100644
>> >> --- a/drivers/i2c/busses/i2c-imx.c
>> >> +++ b/drivers/i2c/busses/i2c-imx.c
>> >> @@ -120,6 +120,7 @@ struct imx_i2c_struct {
>> >>       wait_queue_head_t       queue;
>> >>       unsigned long           i2csr;
>> >>       unsigned int            disable_delay;
>> >> +     unsigned int            ifdr; /* IMX_I2C_IFDR */
>> >>  };
>> >>
>> >>  /** Functions for IMX I2C adapter driver ***************************************
>> >> @@ -210,6 +211,8 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
>> >>
>> >>       dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
>> >>
>> >> +     clk_enable(i2c_imx->clk);
>> >> +     writeb(i2c_imx->ifdr, i2c_imx->base + IMX_I2C_IFDR);
>> >>       /* Enable I2C controller */
>> >>       writeb(0, i2c_imx->base + IMX_I2C_I2SR);
>> >>       writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
>> >> @@ -254,6 +257,7 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
>> >>
>> >>       /* Disable I2C controller */
>> >>       writeb(0, i2c_imx->base + IMX_I2C_I2CR);
>> >> +     clk_disable(i2c_imx->clk);
>> >>  }
>> >>
>> >>  static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
>> >> @@ -273,8 +277,8 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
>> >>       else
>> >>               for (i = 0; i2c_clk_div[i][0] < div; i++);
>> >>
>> >> -     /* Write divider value to register */
>> >> -     writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
>> >> +     /* Store divider value */
>> >> +     i2c_imx->ifdr = i2c_clk_div[i][1];
>> >>
>> >>       if (cpu_is_mx1()) {
>> >>               /*
>> >> @@ -555,7 +559,6 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
>> >>               dev_err(&pdev->dev, "can't get I2C clock\n");
>> >>               goto fail3;
>> >>       }
>> >> -     clk_enable(i2c_imx->clk);
>> >>
>> >>       /* Request IRQ */
>> >>       ret = request_irq(i2c_imx->irq, i2c_imx_isr, 0, pdev->name, i2c_imx);
>> >> @@ -604,7 +607,6 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
>> >>  fail5:
>> >>       free_irq(i2c_imx->irq, i2c_imx);
>> >>  fail4:
>> >> -     clk_disable(i2c_imx->clk);
>> >>       clk_put(i2c_imx->clk);
>> >>  fail3:
>> >>       release_mem_region(i2c_imx->res->start, resource_size(res));
>> >> @@ -641,8 +643,6 @@ static int __exit i2c_imx_remove(struct platform_device *pdev)
>> >>       if (pdata && pdata->exit)
>> >>               pdata->exit(&pdev->dev);
>> >>
>> >> -     /* Disable I2C clock */
>> >> -     clk_disable(i2c_imx->clk);
>> >>       clk_put(i2c_imx->clk);
>> >>
>> >>       release_mem_region(i2c_imx->res->start, resource_size(i2c_imx->res));
>> >> --
>> >> 1.6.0.4
>> >>
>> >>
>> >
>> > --
>> > Pengutronix e.K.                           |                             |
>> > Industrial Linux Solutions                 | http://www.pengutronix.de/  |
>> > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
>> > Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
>> >
>>
>> I don't think we have any suspend/resume routine. And we won't need it any more.
>
> Ups, my bad. I have it in my local tree and didn't realize it isn't
> upstream.
>
> Sascha
>
>
> --
> Pengutronix e.K.                           |                             |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
>

Hi Sascha,

Do I need re-send this patch when I re-send out other patches?

Thanks
Richard