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

Sascha Hauer
2009-10-01T08:00:53Z

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-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.

Ups, my bad. I have it in my local tree and didn't realize it isn't
upstream.

Sascha

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