On Apr 08, 2016 18:00, Peter Meerwald-Stadler wrote: > > > > maybe a #define to explain the name of register 0 > > > > Well this zero is not register nor any kind of command that DS1803 needs to send > > back pots values. > > DS1803 only requires the standard R/W bit to be set as read. > > I used _word_ function series to get back a word (16 bits) as this poti returns > > 16 bits. > > > > How should I named it? > > > > #define NON_COMMAND 0 > > ? > > maybe i2c_transfer() is more appropriate then > > u8 databuf[2]; > struct i2c_msg msgs[2] = { > { .addr = client->addr, .len = sizeof(databuf), .buf = databuf, > .flags = I2C_M_RD } }; > ret = i2c_transfer(client->adapter, msgs, 2); > > this does not send any data to the chip but only reads two bytes Good point. But maybe the better solution would be to use i2c_master_recv? Anyhow I will check both options ;) > > Or should I use different function? (2x i2c_smbus_read_byte?) > > > > The i2c_smbus_read_byte() function also used 0 as command > > for its transfers... > > > > > +static int ds1803_write_raw(struct iio_dev *indio_dev, > > > > + struct iio_chan_spec const *chan, > > > > + int val, int val2, long mask) > > > > +{ > > > > + struct ds1803_data *data = iio_priv(indio_dev); > > > > + int pot = chan->channel; > > > > + > > > > + switch (mask) { > > > > + case IIO_CHAN_INFO_RAW: > > > > + if (val > DS1803_MAX_POS || val < 0) > > > > > > check that val2 is 0 or use .write_raw_get_fmt > > > > At this point I do not know why should I do it, but I will look into that. > > write_raw expects a VAL_INT_PLUS_MICROS per default, passed > in val and val2 > > you can change that with .write_raw_get_fmt (e.g. to expect VAL_INT), > or just make sure that the micros are 0 Thank you for the explanation. -- Slawomir Stepien -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html