Re: [PATCH v3 0/1] iio/scmi: Add reading "raw" attribute.

[Andriy Tryshnivskyy]

Hi Jyoti and Vasyl,

Thanks for your review.
I will provide new patch version soon.

Thanks,
Andriy

On 06.10.21 03:16, Jyoti Bhayana wrote:

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>
>
> Hi Vasyl,
>
> Regarding below question, yes reading raw attribute should be blocked
> if buffer is enabled for that sensor.
>
> > 1. Should we block reading raw attribute and IIO buffer enabled, for for
> > SCMI sensor it can coexist?
>
> PLease see  https://elixir.bootlin.com/linux/latest/source/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c#L667
> as well. It has
>
> case IIO_CHAN_INFO_RAW:
> ret = iio_device_claim_direct_mode(indio_dev);
> if (ret)
> return ret;
> mutex_lock(&st->lock);
> ret = inv_mpu6050_read_channel_data(indio_dev, chan, val);
> mutex_unlock(&st->lock);
> iio_device_release_direct_mode(indio_dev);
> return ret;
>
> Regarding the question below, the answer is yes.
>
> > 2. Should we wrap reading raw attribute implementation in iio_dev->mlock
> > mutex?
>
> Thanks, Jyoti
>
>
>
>
>
> On Tue, Oct 5, 2021 at 5:52 AM Vasyl Vavrychuk
> <vasyl.vavrychuk@xxxxxxxxxxxxxxx> wrote:
> > Hi, Jyoti,
> >
> > > In the code below, why is the logic of enabling and disabling the
> > > sensor in this function?  Generally the function to read the sensor
> > > value is just used for the code to read the sensor values ? and not
> > > enable/disable the sensor
> > But to read sensor value we have to enable it first. Other way to enable
> > sensor we found is, for example:
> >
> >     echo 1 > /sys/bus/iio/devices/.../scan_elements/in_anglvel_x_en
> >
> > But, this command is related to IIO buffers use.
> >
> > Other sensors drivers enable/disable sensor in read raw too, for
> > example, drivers/iio/accel/kxcjk-1013.c has:
> >
> >     case IIO_CHAN_INFO_RAW:
> >             mutex_lock(&data->mutex);
> >             if (iio_buffer_enabled(indio_dev))
> >                     ret = -EBUSY;
> >             else {
> >                     ret = kxcjk1013_set_power_state(data, true);
> >                     ... reading ...
> >                     ret = kxcjk1013_set_power_state(data, false);
> >             }
> >             mutex_unlock(&data->mutex);
> >
> > But, after looking on this code I have some questions:
> >
> > 1. Should we block reading raw attribute and IIO buffer enabled, for for
> > SCMI sensor it can coexist?
> > 2. Should we wrap reading raw attribute implementation in iio_dev->mlock
> > mutex?
> >
> > > >      case IIO_CHAN_INFO_RAW:
> > > > +               sensor_config = FIELD_PREP(SCMI_SENS_CFG_SENSOR_ENABLED_MASK,
> > > > +                                          SCMI_SENS_CFG_SENSOR_ENABLE);
> > > > +               err = sensor->sensor_ops->config_set(
> > > > +                       sensor->ph, sensor->sensor_info->id, sensor_config);
> > > > +               if (err) {
> > > > +                       dev_err(&iio_dev->dev,
> > > > +                               "Error in enabling sensor %s err %d",
> > > > +                               sensor->sensor_info->name, err);
> > > > +                       return err;
> > > > +               }
> > > > +
> > > > +               err = sensor->sensor_ops->reading_get_timestamped(
> > > > +                       sensor->ph, sensor->sensor_info->id,
> > > > +                       sensor->sensor_info->num_axis, readings);
> > > > +               if (err) {
> > > > +                       dev_err(&iio_dev->dev,
> > > > +                               "Error in reading raw attribute for sensor %s err %d",
> > > > +                               sensor->sensor_info->name, err);
> > > > +                       return err;
> > > > +               }
> > > > +
> > > > +               sensor_config = FIELD_PREP(SCMI_SENS_CFG_SENSOR_ENABLED_MASK,
> > > > +                                          SCMI_SENS_CFG_SENSOR_DISABLE);
> > > > +               err = sensor->sensor_ops->config_set(
> > > > +                       sensor->ph, sensor->sensor_info->id, sensor_config);
> > > > +               if (err) {
> > > > +                       dev_err(&iio_dev->dev,
> > > > +                               "Error in enabling sensor %s err %d",
> > > > +                               sensor->sensor_info->name, err);
> > > > +                       return err;
> > > > +               }
> > > > +               /* Check if raw value fits 32 bits */
> > > > +               if (readings[ch->scan_index].value < INT_MIN ||
> > > > +                   readings[ch->scan_index].value > INT_MAX)
> > > > +                       return -ERANGE;
> > > > +               /* Use 32-bit value, since practically there is no need in 64 bits */
> > > > +               *val = (int)readings[ch->scan_index].value;
> > > >
> > > > +               return IIO_VAL_INT;