[alsa-devel] [RFC 16/23] ASoC: omap: mcbsp, mcpdm, dmic: raw read and write endian fix

[Takashi Iwai]

At Sat, 16 Nov 2013 18:09:51 +0200,
Jarkko Nikula wrote:
> 
> On 11/16/2013 02:01 AM, Taras Kondratiuk wrote:
> > From: Victor Kamensky <victor.kamensky at linaro.org>
> > 
> > All OMAP IP blocks expect LE data, but CPU may operate in BE mode.
> > Need to use endian neutral functions to read/write h/w registers.
> > I.e instead of __raw_read[lw] and __raw_write[lw] functions code
> > need to use read[lw]_relaxed and write[lw]_relaxed functions.
> > If the first simply reads/writes register, the second will byteswap
> > it if host operates in BE mode.
> > 
> > Changes are trivial sed like replacement of __raw_xxx functions
> > with xxx_relaxed variant.
> > 
> > Signed-off-by: Victor Kamensky <victor.kamensky at linaro.org>
> > Signed-off-by: Taras Kondratiuk <taras.kondratiuk at linaro.org>
> > ---
> >  sound/soc/omap/mcbsp.c      |   12 ++++++------
> >  sound/soc/omap/omap-dmic.c  |    4 ++--
> >  sound/soc/omap/omap-mcpdm.c |    4 ++--
> >  3 files changed, 10 insertions(+), 10 deletions(-)
> > 
> Looks ok to me by looking at the _relaxed definitions in
> arch/arm/include/asm/io.h.
> 
> Acked-by: Jarkko Nikula <jarkko.nikula at bitmer.com>
> 

What's the reason to use _relaxed version in all places?

I understand this patch is to fix the endianess, so this can be
applied as is, as long as the original code works.  But, still in
general, I wonder how the concurrency is guaranteed by this driver
code...


thanks,

Takashi