+Cc Peter. On Wed, 6 Mar 2019 15:56:06 -0500 Jean-Francois Dagenais <jeff.dagenais@xxxxxxxxx> wrote: > When issuing the write DAC register and write eeprom command, the two > powerdown bits (PD0 and PD1) are assumed by the chip to be present in > the bytes sent. Leaving them at 0 implies "powerdown disabled" which is > a different state that the current one. By adding the current state of > the powerdown in the i2c write, the chip will correctly power-on exactly > like as it is at the moment of store_eeprom call. > > This is documented in MCP4725's datasheet, FIGURE 6-2: "Write Commands > for DAC Input Register and EEPROM" and MCP4726's datasheet, FIGURE 6-3: > "Write All Memory Command". > > Signed-off-by: Jean-Francois Dagenais <jeff.dagenais@xxxxxxxxx> sounds fine to me, but I'd like to give Peter a chance to comment. Give me a poke if it turns out Peter is busy and doesn't get back to us in a week or two. Thanks, Jonathan > --- > drivers/iio/dac/mcp4725.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/iio/dac/mcp4725.c b/drivers/iio/dac/mcp4725.c > index 6ab1f23e5a79..97bb350d1e77 100644 > --- a/drivers/iio/dac/mcp4725.c > +++ b/drivers/iio/dac/mcp4725.c > @@ -98,6 +98,7 @@ static ssize_t mcp4725_store_eeprom(struct device *dev, > > inoutbuf[0] = 0x60; /* write EEPROM */ > inoutbuf[0] |= data->ref_mode << 3; > + inoutbuf[0] |= data->powerdown ? ((data->powerdown_mode+1) << 1) : 0; > inoutbuf[1] = data->dac_value >> 4; > inoutbuf[2] = (data->dac_value & 0xf) << 4; >
