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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <e028c2dc-07e3-71d3-422d-08c6e3a4a99f@sberdevices.ru>
Date:   Fri, 21 Jul 2023 12:58:49 +0300
From:   George Stark <gnstark@...rdevices.ru>
To:     Jonathan Cameron <jic23@...nel.org>
CC:     <lars@...afoo.de>, <neil.armstrong@...aro.org>,
        <khilman@...libre.com>, <jbrunet@...libre.com>,
        <martin.blumenstingl@...glemail.com>,
        <andriy.shevchenko@...ux.intel.com>, <nuno.sa@...log.com>,
        <linux-iio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-amlogic@...ts.infradead.org>, <kernel@...rdevices.ru>
Subject: Re: [PATCH v1 1/1] iio: adc: meson: fix core clock enable/disable
 moment

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@...rdevices.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@...rdevices.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