Re: [PATCH v3 2/3] iio: accel: bmc150: use DMA-safe buffers for regmap bulk reads

[Andy Shevchenko]

On Mon, Aug 31, 2026 at 01:24:50AM +0100, Jonathan Cameron wrote:
> On Thu, 27 Aug 2026 10:05:19 +0300
> Andy Shevchenko <andriy.shevchenko@xxxxxxxxx> wrote:
> > On Tue, Aug 25, 2026 at 02:21:55PM +0530, Yash Suthar wrote:

...

> > >  		j = 0;
> > >  		iio_for_each_active_channel(indio_dev, bit)
> > > -			memcpy(&data->scan.channels[j++], &buffer[i * 3 + bit],
> > > +			memcpy(&data->scan.channels[j++],
> > > +			       &data->fifo_buff[i * 3 + bit],
> > >  			       sizeof(data->scan.channels[0]));  
> > 
> > While this works, I find a bit confusing usage of [j++] and [0] together.
> > 
> > IIUC the below is an equivalent
> > 
> > 		iio_for_each_active_channel(indio_dev, bit) {
> > 			__le16 *val = &data->scan.channels[j++];
> > 
> > 			memcpy(val, &data->fifo_buff[i * 3 + bit], sizeof(val));
> > 		}
> 
> This bit I fully agree with. Much more readable.
> > 
> > and if go further we may use asm/byteorder.h macros instead of plain memcpy().
> > 
> Here I'm lost.  We are just moving little endian values around.
> 
> For that matter if it is a single value, why can't see just assign it?
> 
> 		iio_for_each_active_channel(indio_dev, bit)
> 			data->scan.channels[j++] = data->fifo_buf[i * 3 + bit];

It depends on the alignment. I haven't checked the assignee and the source
for that.  That's why I mentioned byteorder.h (and implying also unaligned.h)
for the cases like put_unaligned_le16(le16_to_cpup(val)). If both sides are
aligned, then yours suggestion will work.

-- 
With Best Regards,
Andy Shevchenko