Re: [PATCH v1 1/1] iio: adc: meson: fix core clock enable/disable moment

[George Stark <gnstark@sberdevices.ru>]

Hello Jonathan

Thanks for the feedback.

On 7/15/23 20:21, Jonathan Cameron wrote:
> On Fri, 14 Jul 2023 22:03:15 +0300
> George Stark <gnstark@sberdevices.ru> wrote:
> 
>> Enable core clock at probe stage and disable it at remove stage.
>> Core clock is responsible for turning on/off the entire SoC module so
>> it should be on before the first module register is touched and be off
>> at very last moment.
>>
>> Signed-off-by: George Stark <gnstark@sberdevices.ru>
> 
> This sounds to me like this should perhaps have a fixes tag?
ack
> 
> Given where it is in the new sequence you can also use
> devm_clk_get_enabled() though that makes a potential backport of
> the fix trickier...
> 
> I'd go with it anyway as it will make this change quite a bit simpler.
ack
> 
> More comments inline
> 
> Jonathan
> 
>> ---
>>   drivers/iio/adc/meson_saradc.c | 20 ++++++++++----------
>>   1 file changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
>> index fe066c9fab83..5a5bb5cc1320 100644
>> --- a/drivers/iio/adc/meson_saradc.c
>> +++ b/drivers/iio/adc/meson_saradc.c
>> @@ -1055,12 +1055,6 @@ static int meson_sar_adc_hw_enable(struct iio_dev *indio_dev)
>>   		goto err_vref;
>>   	}
>>   
>> -	ret = clk_prepare_enable(priv->core_clk);
>> -	if (ret) {
>> -		dev_err(dev, "failed to enable core clk\n");
>> -		goto err_core_clk;
>> -	}
>> -
>>   	regval = FIELD_PREP(MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, 1);
>>   	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
>>   			   MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, regval);
>> @@ -1087,8 +1081,6 @@ static int meson_sar_adc_hw_enable(struct iio_dev *indio_dev)
>>   	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
>>   			   MESON_SAR_ADC_REG3_ADC_EN, 0);
>>   	meson_sar_adc_set_bandgap(indio_dev, false);
>> -	clk_disable_unprepare(priv->core_clk);
>> -err_core_clk:
>>   	regulator_disable(priv->vref);
>>   err_vref:
>>   	meson_sar_adc_unlock(indio_dev);
>> @@ -1116,8 +1108,6 @@ static void meson_sar_adc_hw_disable(struct iio_dev *indio_dev)
>>   
>>   	meson_sar_adc_set_bandgap(indio_dev, false);
>>   
>> -	clk_disable_unprepare(priv->core_clk);
>> -
>>   	regulator_disable(priv->vref);
>>   
>>   	if (!ret)
>> @@ -1420,6 +1410,12 @@ static int meson_sar_adc_probe(struct platform_device *pdev)
>>   			ARRAY_SIZE(meson_sar_adc_iio_channels);
>>   	}
>>   
>> +	ret = clk_prepare_enable(priv->core_clk);
>> +	if (ret) {
>> +		dev_err(dev, "failed to enable core clk\n");
>> +		goto err;
> 
> If clk_prepare_enable() failed, then you shoudl not call clk_disable_unprepare()
yes, but with devm_clk_get_enabled we dont't need this line anymore
> 
>> +	}
>> +
>>   	ret = meson_sar_adc_init(indio_dev);
>>   	if (ret)
>>   		goto err;
>> @@ -1445,17 +1441,21 @@ static int meson_sar_adc_probe(struct platform_device *pdev)
>>   err_hw:
>>   	meson_sar_adc_hw_disable(indio_dev);
>>   err:
>> +	clk_disable_unprepare(priv->core_clk);
> 
> Nothing to do with your patch, but this driver previously did some odd mixing
> of direct returns and going to an empty label which definitely doesn't help
> make this clear to follow.
I made additional patch adding log messages to all errors those can 
break probe stage
> 
>>   	return ret;
>>   }
>>   
>>   static int meson_sar_adc_remove(struct platform_device *pdev)
>>   {
>>   	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>> +	struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
>>   
>>   	iio_device_unregister(indio_dev);
>>   
>>   	meson_sar_adc_hw_disable(indio_dev);
>>   
>> +	clk_disable_unprepare(priv->core_clk);
>> +
>>   	return 0;
>>   }
>>   
> 

-- 
Best regards
George

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