Re: [PATCH 2/3] drivers: iio: adc: LTC2499 support

From: Andy Shevchenko
Date: Tue Aug 23 2022 - 13:38:22 EST


On Mon, Aug 22, 2022 at 11:13 PM Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> On Mon, 22 Aug 2022 15:51:05 +0300
> Ciprian Regus <ciprian.regus@xxxxxxxxxx> wrote:

In reply to Jonathan's comments to answer his question and add more
comments from me.

...

> > Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/2499fe.pdf
> >
> > Signed-off-by: Ciprian Regus <ciprian.regus@xxxxxxxxxx>

Tag block mustn't have the blank line(s).

...

> > #include <linux/iio/iio.h>
> > #include <linux/iio/driver.h>
> > #include <linux/module.h>
> > +#include <linux/property.h>
> why?

device_get_match_data() requires it.

But why not sort them?

> > #include <linux/mod_devicetable.h>

...

> > - *val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
>
> Old code here is less than ideal, should be reading into 3 bytes then using
> the be24 accesors. Please fix whilst here. You will need multiple paths here
> depending on size.
>
> > + *val = (be32_to_cpu(st->buf) >> st->sub_lsb) -
> > + BIT(ddata->chip_info->resolution + 1);

Shouldn't this use some kind of sign_extend()?

Also with a temporary variable for chip info this line can be single.

struct ... *ci = ddata->chip_info;

...BIT(ci->resolution + 1)

...

> > + u32 resolution;

Keep this in a way that the "longer lines go first".

...

> > + resolution = st->common_ddata.chip_info->resolution;
> > + st->sub_lsb = 31 - (resolution + 1);
> > + st->recv_size = resolution / BITS_PER_BYTE + 1;

BITS_TO_BYTES()

...

> > static const struct i2c_device_id ltc2497_id[] = {
> > - { "ltc2497", 0 },
> > + { "ltc2497", TYPE_LTC2497 },
> > + { "ltc2499", TYPE_LTC2499 },

Use pointers here like you have done for the OF table.

> > { }
> > };

...

> > +enum chip_type {
> > + TYPE_LTC2496,
> > + TYPE_LTC2497,
> > + TYPE_LTC2499

Keep trailing comma.

> > +};

--
With Best Regards,
Andy Shevchenko