Re: [RFC 4/4] m68k: coldfire: fix non-standard readX()/writeX() functions

Arnd Bergmann
2026-05-06T19:13:24Z

On Wed, May 6, 2026, at 16:26, Greg Ungerer wrote:

> drivers/dma/mcf-edma-main.c
> Supports big-endian access by setting the big-endian flag of
> the drivers struct fsl_edma_engine. But locally should be using
> ioread32be() and iowrite32be() instead of ioread32() and iowrite32().

I'm still a bit confused about how this works at the moment,
since the drivers/dma/fsl-edma-common.h file already contains
checks for the edma->big_endian flag, which is set in
mcf_edma_probe(). The version after your patch makes sense
to me, but it looks like the existing code cannot work.

> drivers/spi/spi-fsl-dspi.c
> Setting the regmap format_endian flags to use native endian will
> force driver to use appropriate big or little endian access on
> whatever platform it is built for.
>
> These drivers have only been compile tested.

I would suggest marking these as explicit BIG_ENDIAN rather than
NATIVE_ENDIAN. The effect should be the same since coldfire CPUs
cannot run little-endian code, but the way that hardware usually
works is that the endianess is fixed at the bus level to one way
or the other. NATIVE_ENDIAN to me implies that the registers
have configurable endianess that is switched along with the CPU
mode.

Arnd