[PATCH v2 2/2] iio: adc: add Nuvoton NCT720x ADC driver

[Yu-Hsian Yang]

Dear Andy Shevchenko,

Andy Shevchenko <andriy.shevchenko at linux.intel.com> 於 2024年12月4日 週三 下午12:27寫道：
>
> On Wed, Dec 04, 2024 at 11:20:20AM +0800, Yu-Hsian Yang wrote:
> > Andy Shevchenko <andriy.shevchenko at linux.intel.com> 於 2024年12月3日 週二 下午9:50寫道：
> > > On Tue, Dec 03, 2024 at 05:15:40PM +0800, Eason Yang wrote:
>
> ...
>
> > > Second, why do you need two regmaps? How debugfs is supposed to work on the
> > > registers that are 16-bit if you access them via 8-bit regmap and vice versa?
> > >
> > > Can't you simply use bulk reads/writes when it makes sense and drop 16-bit
> > > regmap completely?
> >
> > Read VIN info can use word read or byte read, and other registers
> > should use byte read.
> >
> > For a reviewer's comment, If the i2c controller allows word read then the
> > right thing is to always use it.
>
> But how does this differ to bulk read of two sequential 8-bit offsets?
> And if there is a difference, shouldn't this be addressed on regmap level for
> all? Like testing for the supported flags and access registers based on the
> controller capability and user request.
>

We would explain why we use two regmaps.
In the beginning, we declare a property read-vin-data-size for user to
select byte read or word read.
After discuss with reviewers, we don't need this property.
So I get rid of this property and take word read vin data first.
We can't use regmap_bulk_read since the vin data is not sequential.

For Nuvoton NCT7201/NCT7202 chip,
Take an example as to Vin1:
The VIN reading supports Byte read (One Byte) and Word read (Two Byte)

For Byte read:
First read Index 00h to get VIN1 MSB, then read Index 0Fh Bit 3~7 to
get VIN1 LSB.
Index 0Fh is a shared LSB for all VINs.

For Word read:
Read Index 00h and get 2 Byte (VIN1 MSB and VIN1 LSB).

> --
> With Best Regards,
> Andy Shevchenko
>
>