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

Jonathan Cameron
2023-08-27T17:11:25Z

On Sat, 26 Aug 2023 10:29:20 +0800
Jinjie Ruan <ruanjinjie@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@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;