Re: [PATCH 11/11] iio: pressure-core: st: Provide correct regulator support

Lee Jones
2013-09-04T13:26:46Z

On Wed, 04 Sep 2013, Lars-Peter Clausen wrote:

> On 09/04/2013 03:11 PM, Mark Rutland wrote:
> > Hi Lee,
> >
> > On Wed, Sep 04, 2013 at 10:31:43AM +0100, Lee Jones wrote:
> >> The power to some of the sensors are controlled by regulators. In most
> >> cases these are 'always on', but if not they will fail to work until
> >> the regulator is enabled using the relevant APIs.
> >>
> >> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> >> ---
> >> drivers/iio/pressure/st_pressure_core.c | 13 +++++++++++++
> >> include/linux/iio/common/st_sensors.h | 3 +++
> >> 2 files changed, 16 insertions(+)
> >>
> >> diff --git a/drivers/iio/pressure/st_pressure_core.c b/drivers/iio/pressure/st_pressure_core.c
> >> index f452417..7beed89 100644
> >> --- a/drivers/iio/pressure/st_pressure_core.c
> >> +++ b/drivers/iio/pressure/st_pressure_core.c
> >> @@ -23,6 +23,7 @@
> >> #include <linux/iio/sysfs.h>
> >> #include <linux/iio/trigger.h>
> >> #include <linux/iio/buffer.h>
> >> +#include <linux/regulator/consumer.h>
> >> #include <asm/unaligned.h>
> >>
> >> #include <linux/iio/common/st_sensors.h>
> >> @@ -315,6 +316,15 @@ int st_press_common_probe(struct iio_dev *indio_dev)
> >> indio_dev->modes = INDIO_DIRECT_MODE;
> >> indio_dev->info = &press_info;
> >>
> >> + /* Regulator not mandatory, but if requested we should enable it. */
> >> + pdata->regulator = regulator_get(&indio_dev->dev, "vdd");
> >> + if (!IS_ERR_OR_NULL(pdata->regulator)) {
> >
> > Can regulator_get return NULL? As far as I can see, it either returns a
> > valid reulator pointer or an ERR_PTR value.
> >
> > When you say "if requested", do you mean "if described in the dt"? If
> > so, the above doesn't distunguish between a regulator not being listed
> > and one failing to be got (e.g. if we got EPROBE_DEFER from
> > regulator_get).
> >
> > I think this would be better handled with something like Mark Brown's
> > suggested regulator_get_optional [1,2].

Thanks Mark, I didn't know that existed.

> It can return NULL, but NULL is actually a valid regulator in that case, so
> the check should only be IS_ERR. And yes regulator_get_optional is what
> should be used here.

Okay, I'll use that instead.

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
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