[PATCH -next v2 1/3] iio: adc: at91_adc: Use devm_clk_get_enabled() helper function

[Jonathan Cameron]

On Sat, 26 Aug 2023 10:29:20 +0800
Jinjie Ruan <ruanjinjie at huawei.com> wrote:

> The devm_clk_get_enabled() helper:
>     - calls devm_clk_get()
>     - calls clk_prepare_enable() and registers what is needed in order to
>       call clk_disable_unprepare() when needed, as a managed resource.
> 
> This simplifies the code.
> 
> Signed-off-by: Jinjie Ruan <ruanjinjie at huawei.com>

Hi Jinjie,

Whilst it probably doesn't introduce a 'real' bug this patch does result
in a change of ordering in the remove path that means the irq is now freed
before the clks are disabled which is different from previously.
Two ways to avoid this.
- Do the conversion from patch 2 before this - taking last element out
  of remove and adding it to be the first devm managed cleanup is always
  safe.
- Squash patches 1 and 2

I'd prefer the first option.

Jonathan



> ---
>  drivers/iio/adc/at91_adc.c | 38 ++++++++++----------------------------
>  1 file changed, 10 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index de6650f9c4b1..318e33ce22fb 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -1087,32 +1087,20 @@ static int at91_adc_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> -	st->clk = devm_clk_get(&pdev->dev, "adc_clk");
> +	st->clk = devm_clk_get_enabled(&pdev->dev, "adc_clk");
>  	if (IS_ERR(st->clk)) {
> -		dev_err(&pdev->dev, "Failed to get the clock.\n");
> -		ret = PTR_ERR(st->clk);
> -		goto error_free_irq;
> -	}
> -
> -	ret = clk_prepare_enable(st->clk);
> -	if (ret) {
>  		dev_err(&pdev->dev,
>  			"Could not prepare or enable the clock.\n");
> +		ret = PTR_ERR(st->clk);
>  		goto error_free_irq;
>  	}
>  
> -	st->adc_clk = devm_clk_get(&pdev->dev, "adc_op_clk");
> +	st->adc_clk = devm_clk_get_enabled(&pdev->dev, "adc_op_clk");
>  	if (IS_ERR(st->adc_clk)) {
> -		dev_err(&pdev->dev, "Failed to get the ADC clock.\n");
> -		ret = PTR_ERR(st->adc_clk);
> -		goto error_disable_clk;
> -	}
> -
> -	ret = clk_prepare_enable(st->adc_clk);
> -	if (ret) {
>  		dev_err(&pdev->dev,
>  			"Could not prepare or enable the ADC clock.\n");
> -		goto error_disable_clk;
> +		ret = PTR_ERR(st->adc_clk);
> +		goto error_free_irq;
>  	}
>  
>  	/*
> @@ -1132,7 +1120,7 @@ static int at91_adc_probe(struct platform_device *pdev)
>  	if (!st->startup_time) {
>  		dev_err(&pdev->dev, "No startup time available.\n");
>  		ret = -EINVAL;
> -		goto error_disable_adc_clk;
> +		goto error_free_irq;
>  	}
>  	ticks = (*st->caps->calc_startup_ticks)(st->startup_time, adc_clk_khz);
>  
> @@ -1160,7 +1148,7 @@ static int at91_adc_probe(struct platform_device *pdev)
>  	ret = at91_adc_channel_init(idev);
>  	if (ret < 0) {
>  		dev_err(&pdev->dev, "Couldn't initialize the channels.\n");
> -		goto error_disable_adc_clk;
> +		goto error_free_irq;
>  	}
>  
>  	init_waitqueue_head(&st->wq_data_avail);
> @@ -1175,19 +1163,19 @@ static int at91_adc_probe(struct platform_device *pdev)
>  		ret = at91_adc_buffer_init(idev);
>  		if (ret < 0) {
>  			dev_err(&pdev->dev, "Couldn't initialize the buffer.\n");
> -			goto error_disable_adc_clk;
> +			goto error_free_irq;
>  		}
>  
>  		ret = at91_adc_trigger_init(idev);
>  		if (ret < 0) {
>  			dev_err(&pdev->dev, "Couldn't setup the triggers.\n");
>  			at91_adc_buffer_remove(idev);
> -			goto error_disable_adc_clk;
> +			goto error_free_irq;
>  		}
>  	} else {
>  		ret = at91_ts_register(idev, pdev);
>  		if (ret)
> -			goto error_disable_adc_clk;
> +			goto error_free_irq;
>  
>  		at91_ts_hw_init(idev, adc_clk_khz);
>  	}
> @@ -1207,10 +1195,6 @@ static int at91_adc_probe(struct platform_device *pdev)
>  	} else {
>  		at91_ts_unregister(st);
>  	}
> -error_disable_adc_clk:
> -	clk_disable_unprepare(st->adc_clk);
> -error_disable_clk:
> -	clk_disable_unprepare(st->clk);
>  error_free_irq:
>  	free_irq(st->irq, idev);
>  	return ret;
> @@ -1228,8 +1212,6 @@ static int at91_adc_remove(struct platform_device *pdev)
>  	} else {
>  		at91_ts_unregister(st);
>  	}
> -	clk_disable_unprepare(st->adc_clk);
> -	clk_disable_unprepare(st->clk);
>  	free_irq(st->irq, idev);
>  
>  	return 0;