Re: [PATCH v6 1/3] iio: adc: Fix incorrect reading when datarate changed in single mode

[Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>]

On Mon, 13 Jul 2026 12:53:49 +0200
Jakub Szczudło <jakubszczudlo40@gmail.com> wrote:

> > > +     ret = i2c_master_recv(data->client, (char *)&buffer, sizeof(buffer));  
> >
> > In theory this can return short (generally reflects a misbehaving device).
> >  
> > > +     if (ret < 0) {
> > > +             dev_err(&data->client->dev, "I2C read fail: %d\n", ret);
> > > +             return true;
> > > +     }  
> >
> >         if (ret < sizeof(buffer))
> >                 return -EIO;
> >  
> I have checked the source code for i2c_master_recv and it should
> return sizeof(buffer)
> or errno code. Also David and Andy in v4 told me to delete such check.

Fair point on it not being needed.  Gah, I get my i2c functions confused.
Only the multi transfer ones can return partial success.

> > > +
> > > +     return FIELD_GET(ADS1100_CFG_ST_BSY, buffer[2]);
> > > +}
> > > +
> > > +static int ads1100_poll_data_ready(struct ads1100_data *data)
> > > +{
> > > +     int data_rate_Hz = ads1100_data_rate[FIELD_GET(ADS1100_DR_MASK, data->config)];
> > > +     /* To be sure we wait 5 times more than data rate */
> > > +     unsigned long wait_time_us = DIV_ROUND_CLOSEST(USEC_PER_SEC, 5 * data_rate_Hz);
> > > +     bool data_ready;
> > > +     u8 buffer[3];
> > > +     int ret;
> > > +
> > > +     /* To be sure that polled value will have value after config change */
> > > +     ret = i2c_master_recv(data->client, (char *)&buffer, sizeof(buffer));
> > > +     if (ret < 0) {
> > > +             dev_err(&data->client->dev, "I2C read fail: %d\n", ret);
> > > +             return ret;
> > > +     }  
> >         if (ret < sizeof(buffer))
> >                 reutrn -EIO;  
> > > +
> > > +     return readx_poll_timeout(ads1100_new_data_not_ready, data,
> > > +                              data_ready, data_ready != 0,  
> >
> > Kind of related to David's question: sashiko doesn't like this.
> > https://sashiko.dev/#/patchset/20260711184414.1013686-1-jakubszczudlo40%40gmail.com
> > I think I agree with it.  Generally need to check for errors in the polling
> > routing as well and return those if seen (in data_ready I think at the end?)
> >  
> > > +                              wait_time_us, ADS1100_MAX_DRDY_TIMEOUT_US);
> > > +}  
> >  
> sure I will update the function to return int instead of bool and
> check for errors
> 
>