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

Ardelean, Alexandru
2020-07-13T05:08:05Z

On Sun, 2020-07-12 at 13:02 +0100, Jonathan Cameron wrote:
> On Thu, 9 Jul 2020 17:21:56 +0200
> Artur Rojek <contact@artur-rojek.eu> 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@artur-rojek.eu>
> > Tested-by: Paul Cercueil <paul@crapouillou.net>
> 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;
> > }