Re: [PATCH v4] iio: adc: Add TI ADS1015 ADC driver support

[Michael Welling]

On Tue, Feb 09, 2016 at 12:41:35AM +0530, Sricharan wrote:
> Hi,
> 
> > -----Original Message-----
> > From: Michael Welling [mailto:mwelling79@xxxxxxxxx] On Behalf Of Michael
> > Welling
> > Sent: Monday, February 08, 2016 10:07 PM
> > To: Wolfram Sang
> > Cc: Daniel Baluta; Jonathan Cameron; Hartmut Knaack; Lars-Peter Clausen;
> > Peter Meerwald-Stadler; Linux Kernel Mailing List;
> linux-iio@xxxxxxxxxxxxxxx;
> > Lucas De Marchi; Andy Gross; Pramod Gurav; Bjorn Andersson; Guenter
> > Roeck; eibach@xxxxxxxx; Sricharan R; linux-arm-msm@xxxxxxxxxxxxxxx
> > Subject: Re: [PATCH v4] iio: adc: Add TI ADS1015 ADC driver support
> > 
> > On Mon, Feb 08, 2016 at 11:25:00AM +0100, Wolfram Sang wrote:
> > > On Fri, Feb 05, 2016 at 06:32:45PM -0600, Michael Welling wrote:
> > > > On Fri, Feb 05, 2016 at 09:32:34PM +0200, Daniel Baluta wrote:
> > > > > >> +static int ads1015_read_raw(struct iio_dev *indio_dev,
> > > > > >> +                         struct iio_chan_spec const *chan, int
> *val,
> > > > > >> +                         int *val2, long mask) {
> > > > > >> +     int ret, idx;
> > > > > >> +     struct ads1015_data *data = iio_priv(indio_dev);
> > > > > >> +
> > > > > >> +     mutex_lock(&data->lock);
> > > > > >> +     switch (mask) {
> > > > > >> +     case IIO_CHAN_INFO_RAW:
> > > > > >> +             if (iio_buffer_enabled(indio_dev)) {
> > > > > >> +                     ret = -EBUSY;
> > > > > >> +                     break;
> > > > > >> +             }
> > > > > >> +
> > > > > >> +             ret = ads1015_set_power_state(data, true);
> > > > > >> +             if (ret < 0)
> > > > > >> +                     break;
> > > > > >
> > > > > > Just tested the driver on a Dragonboard 410C with a robotics
> > > > > > mezzanine that I designed.
> > > > > >
> > > > > > The above ads1015_set_power_state(data, true) is always returning
> -
> > EINVAL.
> > > > > >
> > > > > > Any ideas why that would be happening?
> > > > > > I think it may be the return from pm_runtime_get_sync?
> > > > >
> > > > > Can you confirm that pm_runtime_get_sync fails? Using some printk?
> > > > >
> > > > > Also adding printks in suspend/resume function would be helpful.
> > > > > Do you have CONFIG_PM enabled?
> > > > >
> > > >
> > > > Indeed it is the pm_runtime_get_sync that fails with a -EINVAL.
> > > >
> > > > > >
> > > > > > When I comment out the break the readings come back but are not
> > updated continually.
> > > > > > If I read in_voltage0-voltage1_raw then in_voltage0_raw the value
> is
> > updated.
> > > > >
> > > > > I guess this is normal if set_power_state fails.
> > > >
> > > > The hwmod driver works fine BTW.
> > > >
> > > > My guess is there is an issue with the qup i2c driver seeing as it
> > > > has worked on other system without issue.
> > > >
> > > > CC'd some the latest developer on the qup i2c driver.
> > > >
> > > > I2C guys have any ideas on this?
> > > >
> > >
> > > Adding some more people who recently worked on this. Might be nice to
> > > know which kernel version you are using.
> > >
>  Which i2c bus is this connected to ? I can give a try with 410c to see why
> pm_runtime_get_sync from qup
>  fails.

It is on the lowspeed header. Here is my devicetree entry:

                 i2c@78b6000 {
                 /* On Low speed expansion */
                         label = "LS-I2C0";
                         status = "okay";
 
                         pca: pca@40 {
                                 compatible = "nxp,pca9685-pwm";
                                 #pwm-cells = <2>;
                                 reg = <0x40>;
                         };
 
                         adc: adc@48 {
                                 compatible = "ti,ads1015";
                                 reg = <0x48>;
                         };
                 };

> 
> Regards,
>   Sricharan
> 
> 
>