Re: [PATCH v8 2/6] IIO: Ingenic JZ47xx: Error check clk_enable calls.

[Ardelean, Alexandru]

On Sun, 2020-07-12 at 13:02 +0100, Jonathan Cameron wrote:
> On Thu,  9 Jul 2020 17:21:56 +0200
> Artur Rojek <contact@xxxxxxxxxxxxxx> wrote:
> 
> > Introduce error checks for the clk_enable calls used in this driver.
> > As part of the changes, move clk_enable/clk_disable calls out of
> > ingenic_adc_set_config and into respective logic of its callers.
> > 
> > Signed-off-by: Artur Rojek <contact@xxxxxxxxxxxxxx>
> > Tested-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> Applied.
> 
> Thanks,
> 
> Jonathan
> 
> > ---
> > 
> >  Changes:
> > 
> >  v6: new patch
> > 
> >  v7: no change
> > 
> >  v8: move `clk_disable` outside the lock
> > 
> >  drivers/iio/adc/ingenic-adc.c | 25 +++++++++++++++++++++----
> >  1 file changed, 21 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/ingenic-adc.c b/drivers/iio/adc/ingenic-
> > adc.c
> > index 39c0a609fc94..c1946a9f1cca 100644
> > --- a/drivers/iio/adc/ingenic-adc.c
> > +++ b/drivers/iio/adc/ingenic-adc.c
> > @@ -73,7 +73,6 @@ static void ingenic_adc_set_config(struct ingenic_adc
> > *adc,
> >  {
> >  	uint32_t cfg;
> >  
> > -	clk_enable(adc->clk);
> >  	mutex_lock(&adc->lock);
> >  
> >  	cfg = readl(adc->base + JZ_ADC_REG_CFG) & ~mask;
> > @@ -81,7 +80,6 @@ static void ingenic_adc_set_config(struct ingenic_adc
> > *adc,
> >  	writel(cfg, adc->base + JZ_ADC_REG_CFG);
> >  
> >  	mutex_unlock(&adc->lock);
> > -	clk_disable(adc->clk);
> >  }
> >  
> >  static void ingenic_adc_enable(struct ingenic_adc *adc,
> > @@ -124,6 +122,8 @@ static int ingenic_adc_write_raw(struct iio_dev
> > *iio_dev,
> >  				 long m)
> >  {
> >  	struct ingenic_adc *adc = iio_priv(iio_dev);
> > +	struct device *dev = iio_dev->dev.parent;
> > +	int ret;
> >  
> >  	switch (m) {
> >  	case IIO_CHAN_INFO_SCALE:
> > @@ -131,6 +131,14 @@ static int ingenic_adc_write_raw(struct iio_dev
> > *iio_dev,
> >  		case INGENIC_ADC_BATTERY:
> >  			if (!adc->soc_data->battery_vref_mode)
> >  				return -EINVAL;
> > +
> > +			ret = clk_enable(adc->clk);
> > +			if (ret) {
> > +				dev_err(dev, "Failed to enable clock:
> > %d\n",
> > +					ret);
> > +				return ret;
> > +			}
> > +
> >  			if (val > JZ_ADC_BATTERY_LOW_VREF) {
> >  				ingenic_adc_set_config(adc,
> >  						       JZ_ADC_REG_CFG_BAT_M
> > D,
> > @@ -142,6 +150,9 @@ static int ingenic_adc_write_raw(struct iio_dev
> > *iio_dev,
> >  						       JZ_ADC_REG_CFG_BAT_M
> > D);
> >  				adc->low_vref_mode = true;
> >  			}
> > +
> > +			clk_disable(adc->clk);
> > +
> >  			return 0;
> >  		default:
> >  			return -EINVAL;
> > @@ -317,6 +328,13 @@ static int ingenic_adc_read_chan_info_raw(struct
> > ingenic_adc *adc,
> >  					  int *val)
> >  {
> >  	int bit, ret, engine = (chan->channel == INGENIC_ADC_BATTERY);
> > +	struct device *dev = iio_priv_to_dev(adc)->dev.parent;

This uses iio_priv_to_dev(), which should be removed [if it hasn't been
already].
Also, with the iio_dev_opaque struct/type, using the iio_priv_to_dev()
helper shouldn't work, or should give undefined behavior, as the offset to
the private data should be matched against iio_dev_opaque (and not
iio_dev).

Looking at this code, it looks like ingenic_adc_read_chan_info_raw() can
take an 'indio_dev' reference and obtain the private information via
iio_priv()

Maybe [for some] there's a question as to why iio_priv_to_dev() is being
removed.
The answer is: because the iio_dev_opaque struct/type was introduced to
hide some iio_dev [INTERN] fields; the main reason for hiding them [aside
from good coding practice, and because they belong to the IIO framework] is
to not have to review new drivers being copied/adapted from old drivers.

Naturally, the iio_priv_to_dev() could have been kept around [in a reworked
form], but it didn't make much sense, since most users of iio_priv_to_dev()
could access a reference to indio_dev without much/any hassle.

> > +
> > +	ret = clk_enable(adc->clk);
> > +	if (ret) {
> > +		dev_err(dev, "Failed to enable clock: %d\n", ret);
> > +		return ret;
> > +	}
> >  
> >  	/* We cannot sample AUX/AUX2 in parallel. */
> >  	mutex_lock(&adc->aux_lock);
> > @@ -325,7 +343,6 @@ static int ingenic_adc_read_chan_info_raw(struct
> > ingenic_adc *adc,
> >  		ingenic_adc_set_config(adc, JZ_ADC_REG_CFG_AUX_MD, bit);
> >  	}
> >  
> > -	clk_enable(adc->clk);
> >  	ret = ingenic_adc_capture(adc, engine);
> >  	if (ret)
> >  		goto out;
> > @@ -342,8 +359,8 @@ static int ingenic_adc_read_chan_info_raw(struct
> > ingenic_adc *adc,
> >  
> >  	ret = IIO_VAL_INT;
> >  out:
> > -	clk_disable(adc->clk);
> >  	mutex_unlock(&adc->aux_lock);
> > +	clk_disable(adc->clk);
> >  
> >  	return ret;
> >  }