Re: [PATCH v2 2/2] iio: dac: dac8163: Add driver for DAC8163

[Siratul Islam]

July 26, 2026 at 8:10 PM, "Lukas" <lukas.metz@xxxxxxx mailto:lukas.metz@xxxxxxx?to=%22Lukas%22%20%3Clukas.metz%40gmx.net%3E > wrote:


> 
> On Wed, Jul 08, 2026 at 09:58:13PM +0600, Siratul Islam wrote:
> 
> > 
> > +
> >  + const struct reg_default reg_defaults[] = {
> >  + {
> >  + .reg = CMD_SET(CMD_WRITE_UPDATE, 0),
> >  + .def = info->default_output_reg,
> >  + },
> >  + {
> >  + .reg = CMD_SET(CMD_WRITE_UPDATE, 1),
> >  + .def = info->default_output_reg,
> >  + },
> >  + };
> >  +
> >  + const struct regmap_config regmap_config = {
> >  + .reg_bits = 8,
> >  + .val_bits = 16,
> >  +
> >  + .max_register = CMD_REF << 3,
> >  + .cache_type = REGCACHE_MAPLE,
> >  +
> >  + .volatile_reg = dac8163_reg_false,
> >  +
> >  + .reg_defaults = reg_defaults,
> >  + .num_reg_defaults = ARRAY_SIZE(reg_defaults),
> >  + };
> >  Why are these defined inside probe? Should be defined outside the function.
> > 
> The default values after reset are different for the compatible devices
> (0 for the dacxxx2 devices and mid-scale for the dacxxx3 devices).
> So these are runtime dependent. The alternative would be to have two
> regmap_configs for the two device types and add these to the chip_info.
> Or do you have another suggestion?
You don't need two regmap_configs. The way I would do it is, move the "regmap_config" out of probe and name it something 
like "dac8563_regmap_config". And in chip info struct, replace "default_output_reg" with "reg_defaults[]". 
Then for each "dacxxxx_chip_info" define the appropriate "reg_defaults" configuration.

This way you can do

struct regmap_config regmap_config = dac8563_regmap_config;
...
regmap_config.reg_defaults = info->reg_defaults;
regmap_config.num_reg_defaults = ARRAY_SIZE(info->reg_defaults);

A bit of work, but it would ensure most of the work is done at compile time,
and we avoid reconstructing these sructs everytime probe runs.

> 
> Best regards
> 
> Lukas
>
--
Best regards,
Sirat