Re: [PATCH 2/2] iio: adc: Add support for AD4000

[Jonathan Cameron]

On Sat, 23 Mar 2024 16:53:17 -0500

> > +
> > +       /*
> > +        * DMA (thus cache coherency maintenance) requires the
> > +        * transfer buffers to live in their own cache lines.
> > +        */
> > +       union {
> > +               struct {
> > +                       u8 sample_buf[4];
> > +                       s64 timestamp;  
> 
> Usually we see __aligned(8) applied to the timestamp (I'm guessing
> some archs need it?)
> 
Good spot. Yes, x86_32 is the one that we most commonly refer to for this.
It aligns s64 to only 32 bits whereas IIO ABI is always naturally aligned.

> > +               } scan;
> > +               u8 d8[2];
> > +       } data __aligned(IIO_DMA_MINALIGN);
> > +};