Re: [PATCH] iio: dac: mcp4725: add missing powerdown bits in store eeprom

Peter Meerwald-Stadler
2019-03-10T11:31:19Z

> +Cc Peter.

> > 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@gmail.com>

> 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.

I'd suggest whitespace around the + operator, otherwise

Acked-by: Peter Meerwald-Stadler <pmeerw@pmeerw.net>

> > ---
> > 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;
> >
>

--

Peter Meerwald-Stadler
Mobile: +43 664 24 44 418