Re: [PATCH 3/3] i2c-pnx: Disable/enable clocks only when needed to reduce power

[Ben Dooks <ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org>]

On Tue, Mar 16, 2010 at 03:55:38PM -0700, wellsk40-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org wrote:
> From: Kevin Wells <wellsk40-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> 
> Enable I2C peripheral clocking at the start of a transfer and
> disable on transfer completion to reduce peripheral power use
> when bus is not in use.

I'm going to leave this one for -next as it isn't really a bugfix.
 
> Signed-off-by: Kevin Wells <wellsk40-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/i2c/busses/i2c-pnx.c |   33 +++++++--------------------------
>  1 files changed, 7 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-pnx.c b/drivers/i2c/busses/i2c-pnx.c
> index 6bb6ff7..23bd556 100644
> --- a/drivers/i2c/busses/i2c-pnx.c
> +++ b/drivers/i2c/busses/i2c-pnx.c
> @@ -448,6 +448,8 @@ i2c_pnx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
>  		"%s(): entering: %d messages, stat = %04x.\n",
>  		__func__, num, ioread32(I2C_REG_STS(alg_data)));
>  
> +	clk_enable(alg_data->clk);
> +
>  	bus_reset_if_active(alg_data);
>  
>  	/* Process transactions in a loop. */
> @@ -516,6 +518,8 @@ i2c_pnx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
>  
>  	bus_reset_if_active(alg_data);
>  
> +	clk_disable(alg_data->clk);
> +
>  	/* Cleanup to be sure... */
>  	alg_data->mif.buf = NULL;
>  	alg_data->mif.len = 0;
> @@ -539,29 +543,6 @@ static struct i2c_algorithm pnx_algorithm = {
>  	.functionality = i2c_pnx_func,
>  };
>  
> -#ifdef CONFIG_PM
> -static int i2c_pnx_controller_suspend(struct platform_device *pdev,
> -				      pm_message_t state)
> -{
> -	struct i2c_pnx_algo_data *alg_data = platform_get_drvdata(pdev);
> -
> -	/* FIXME: shouldn't this be clk_disable? */
> -	clk_enable(alg_data->clk);
> -
> -	return 0;
> -}
> -
> -static int i2c_pnx_controller_resume(struct platform_device *pdev)
> -{
> -	struct i2c_pnx_algo_data *alg_data = platform_get_drvdata(pdev);
> -
> -	return clk_enable(alg_data->clk);
> -}
> -#else
> -#define i2c_pnx_controller_suspend	NULL
> -#define i2c_pnx_controller_resume	NULL
> -#endif
> -
>  static int __devinit i2c_pnx_probe(struct platform_device *pdev)
>  {
>  	unsigned long tmp;
> @@ -665,6 +646,9 @@ static int __devinit i2c_pnx_probe(struct platform_device *pdev)
>  	dev_dbg(&pdev->dev, "%s: Master at %#8x, irq %d.\n",
>  	       alg_data->adapter.name, i2c_pnx->base, i2c_pnx->irq);
>  
> +	/* Disable clock until needed */
> +	clk_disable(alg_data->clk);
> +
>  	return 0;
>  
>  out_irq:
> @@ -692,7 +676,6 @@ static int __devexit i2c_pnx_remove(struct platform_device *pdev)
>  
>  	free_irq(i2c_pnx->irq, alg_data);
>  	i2c_del_adapter(&alg_data->adapter);
> -	clk_disable(alg_data->clk);
>  	iounmap(alg_data->ioaddr);
>  	release_mem_region(i2c_pnx->base, I2C_PNX_REGION_SIZE);
>  	clk_put(alg_data->clk);
> @@ -709,8 +692,6 @@ static struct platform_driver i2c_pnx_driver = {
>  	},
>  	.probe = i2c_pnx_probe,
>  	.remove = __devexit_p(i2c_pnx_remove),
> -	.suspend = i2c_pnx_controller_suspend,
> -	.resume = i2c_pnx_controller_resume,
>  };
>  
>  static int __init i2c_adap_pnx_init(void)
> -- 
> 1.6.6
> 
> --
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-- 
Ben (ben-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org, http://www.fluff.org/)

  'a smiley only costs 4 bytes'