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

Richard Zhao
2009-10-01T07:56:29Z

On Thu, Oct 1, 2009 at 3:34 PM, Sascha Hauer <s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> 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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>
>> 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
>>
>>
>
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>

I don't think we have any suspend/resume routine. And we won't need it any more.

Thanks
Richard