linux-kernel - Re: [PATCH v2] iio: adc: lpc18xx_adc: Convert probe to device managed version

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Message-ID: <YWwmFDF7Lig2rAuo@Andryuu.br>
Date:   Sun, 17 Oct 2021 10:33:08 -0300
From:   André Gustavo Nakagomi Lopez <andregnl@....br>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     linux-iio@...r.kernel.org, lars@...afoo.de, vz@...ia.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iio: adc: lpc18xx_adc: Convert probe to device
 managed version

On Sun, Oct 17, 2021 at 12:35:33PM +0100, Jonathan Cameron wrote:
> On Fri, 15 Oct 2021 15:47:12 -0300
> André Gustavo Nakagomi Lopez <andregnl@....br> wrote:
> 
> > The remove function and the goto sections are not necessary if devm
> > functions are used.
> > 
> > Convert device register to devm version. Add hook functions to release
> > device resources, and use them inside probe with devm_add_action,
> > which will release resources on driver detach.
> > 
> > To maintain the order of which device resources were released/reseted,
> > register the hook functions as soon as resources are obtained/initialized.
> > Since devres actions are called on driver detach, the remove
> > function and the error-handling goto sections are no longer necessary.
> > 
> > Signed-off-by: André Gustavo Nakagomi Lopez <andregnl@....br>
> 
> Hi André
> 
> Looks good to me, but I did notice an unrelated issue whilst looking at this driver.
> Comment on that inline.  Follow up patch welcome!
> 
> Applied to the togreg branch of iio.git and pushed out as testing to let 0-day
> see if it can find anything we missed.
> 
> Thanks,
> 
> Jonathan
> 
> 
> 
> > ---
> > Change log V1 -> V2:
> >        -Renamed lpc18xx_clk_disable_unprepare function
> >        -Removed platform_set_drvdata(pdev, indio_dev)
> >        -Renamed lpc18xx_writel to lpc18xx_clear_cr_reg
> >        -devm_iio_device_register now returns directly in the end of probe function
> >  drivers/iio/adc/lpc18xx_adc.c | 61 ++++++++++++++++++-----------------
> >  1 file changed, 31 insertions(+), 30 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/lpc18xx_adc.c b/drivers/iio/adc/lpc18xx_adc.c
> > index 3566990ae87d..7d50107427ac 100644
> > --- a/drivers/iio/adc/lpc18xx_adc.c
> > +++ b/drivers/iio/adc/lpc18xx_adc.c
> > @@ -115,6 +115,23 @@ static const struct iio_info lpc18xx_adc_info = {
> >  	.read_raw = lpc18xx_adc_read_raw,
> >  };
> >  
> > +static void lpc18xx_clear_cr_reg(void *data)
> > +{
> > +	struct lpc18xx_adc *adc = data;
> > +
> > +	writel(0, adc->base + LPC18XX_ADC_CR);
> > +}
> > +
> > +static void lpc18xx_clk_disable(void *clk)
> > +{
> > +	clk_disable_unprepare(clk);
> > +}
> > +
> > +static void lpc18xx_regulator_disable(void *vref)
> > +{
> > +	regulator_disable(vref);
> > +}
> > +
> >  static int lpc18xx_adc_probe(struct platform_device *pdev)
> >  {
> >  	struct iio_dev *indio_dev;
> > @@ -127,7 +144,6 @@ static int lpc18xx_adc_probe(struct platform_device *pdev)
> >  	if (!indio_dev)
> >  		return -ENOMEM;
> >  
> > -	platform_set_drvdata(pdev, indio_dev);
> >  	adc = iio_priv(indio_dev);
> >  	adc->dev = &pdev->dev;
> >  	mutex_init(&adc->lock);
> > @@ -163,44 +179,30 @@ static int lpc18xx_adc_probe(struct platform_device *pdev)
> >  		return ret;
> >  	}
> >  
> > +	ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_regulator_disable, adc->vref);
> > +	if (ret)
> > +		return ret;
> > +
> >  	ret = clk_prepare_enable(adc->clk);
> >  	if (ret) {
> >  		dev_err(&pdev->dev, "unable to enable clock\n");
> > -		goto dis_reg;
> > +		return ret;
> 
> Unrelated but clk_get_rate() as called before the clk_prepare_enable() is not guaranteed
> to work.   So a good follow up patch would reorder that to be after the clk is turned on.
> 
> 
> >  	}
> >  
> > +	ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_clk_disable,
> > +				       adc->clk);
> > +	if (ret)
> > +		return ret;
> > +
> >  	adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) |
> >  			LPC18XX_ADC_CR_PDN;
> >  	writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR);
> >  
> > -	ret = iio_device_register(indio_dev);
> > -	if (ret) {
> > -		dev_err(&pdev->dev, "unable to register device\n");
> > -		goto dis_clk;
> > -	}
> > -
> > -	return 0;
> > -
> > -dis_clk:
> > -	writel(0, adc->base + LPC18XX_ADC_CR);
> > -	clk_disable_unprepare(adc->clk);
> > -dis_reg:
> > -	regulator_disable(adc->vref);
> > -	return ret;
> > -}
> > -
> > -static int lpc18xx_adc_remove(struct platform_device *pdev)
> > -{
> > -	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> > -	struct lpc18xx_adc *adc = iio_priv(indio_dev);
> > -
> > -	iio_device_unregister(indio_dev);
> > -
> > -	writel(0, adc->base + LPC18XX_ADC_CR);
> > -	clk_disable_unprepare(adc->clk);
> > -	regulator_disable(adc->vref);
> > +	ret = devm_add_action_or_reset(&pdev->dev, lpc18xx_clear_cr_reg, adc);
> > +	if (ret)
> > +		return ret;
> >  
> > -	return 0;
> > +	return devm_iio_device_register(&pdev->dev, indio_dev);
> >  }
> >  
> >  static const struct of_device_id lpc18xx_adc_match[] = {
> > @@ -211,7 +213,6 @@ MODULE_DEVICE_TABLE(of, lpc18xx_adc_match);
> >  
> >  static struct platform_driver lpc18xx_adc_driver = {
> >  	.probe	= lpc18xx_adc_probe,
> > -	.remove	= lpc18xx_adc_remove,
> >  	.driver	= {
> >  		.name = "lpc18xx-adc",
> >  		.of_match_table = lpc18xx_adc_match,
> 

Ok. Thank you for the review, I will work on the change.