Re: [PATCH v4 1/3] iio: adc: Fix incorrect reading when datarate changed in single mode

[Jonathan Cameron]

On Sat, 27 Jun 2026 17:31:24 -0500
David Lechner <dlechner@xxxxxxxxxxxx> wrote:

> On 6/22/26 5:15 PM, Jakub Szczudlo wrote:
> > When device is suspended and it is in single mode then changing
> > datarate doesn't make it actual wait for new measurement, so to
> > be sure that read after change is correct functions that changes
> > datarate and gain will wait for new data.
> > 
> > Fixes: 541880542f2b ("iio: adc: Add TI ADS1100 and ADS1000")
> > Signed-off-by: Jakub Szczudlo <jakubszczudlo40@xxxxxxxxx>
> > ---
> >  drivers/iio/adc/ti-ads1100.c | 74 ++++++++++++++++++++++++++++++++++--
> >  1 file changed, 70 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/ti-ads1100.c b/drivers/iio/adc/ti-ads1100.c
> > index 9fe8d54cce83..e3c801381434 100644
> > --- a/drivers/iio/adc/ti-ads1100.c
> > +++ b/drivers/iio/adc/ti-ads1100.c
> > @@ -15,6 +15,7 @@
> >  #include <linux/module.h>
> >  #include <linux/init.h>
> >  #include <linux/i2c.h>
> > +#include <linux/iopoll.h>
> >  #include <linux/mutex.h>
> >  #include <linux/property.h>
> >  #include <linux/pm_runtime.h>
> > @@ -43,6 +44,9 @@
> >  static const int ads1100_data_rate[] = { 128, 32, 16, 8 };
> >  static const int ads1100_data_rate_bits[] = { 12, 14, 15, 16 };
> >  
> > +/* Timeout based on the minimum sample rate of 8 SPS (7.5s) */
> > +#define ADS1100_MAX_DRDY_TIMEOUT_US	7500000
> > +
> >  struct ads1100_data {
> >  	struct i2c_client *client;
> >  	struct regulator *reg_vdd;
> > @@ -123,10 +127,49 @@ static int ads1100_get_adc_result(struct ads1100_data *data, int chan, int *val)
> >  	return 0;
> >  }
> >  
> > +static bool ads1100_new_data_not_ready(struct ads1100_data *data)
> > +{
> > +	int ret;
> > +	u8 buffer[3];
> > +
> > +	ret = i2c_master_recv(data->client, (char *)&buffer, sizeof(buffer));  
> 
> Do we actually need the cast here? char * is like void * and should not need it.
Hi David,

Any more background on this?  The void * implicit cast thing is in the
c standard.  I don't think there is anything equivalent for char *

Thanks,

Jonathan