On Mon, Apr 29, 2019 at 10:19 AM Geert Uytterhoeven <ge...@linux-m68k.org> wrote: > > The generic definitions of mmio_{read,write}{16,32}be() in lib/iomap.c > assume that the {read,write}[wl]() I/O accessors always use little > endian accesses, and swap the result. > > However, the Coldfire versions of the {read,write}[wl]() I/O accessors are > special, in that they use native big endian instead of little endian for > accesses to the on-SoC peripheral block, thus violating the assumption. > > Fix this by providing our own variants, using the raw accessors, > reinstating the old behavior. This is fine on m68k, as no special > barriers are needed, and also avoids swapping data twice. > > Reported-by: Angelo Dureghello <ang...@sysam.it> > Fixes: aecc787c06f4300f ("iomap: Use non-raw io functions for > io{read|write}XXbe") > Signed-off-by: Geert Uytterhoeven <ge...@linux-m68k.org> > --- > This can be reverted later, after this oddity of the Coldfire I/O > support has been fixed, and drivers have been updated. > --- > arch/m68k/include/asm/io.h | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/m68k/include/asm/io.h b/arch/m68k/include/asm/io.h > index aabe6420ead2a599..d47e7384681ab1cd 100644 > --- a/arch/m68k/include/asm/io.h > +++ b/arch/m68k/include/asm/io.h > @@ -8,6 +8,12 @@ > #include <asm/io_mm.h> > #endif > > +#define mmio_read16be(addr) __raw_readw(addr) > +#define mmio_read32be(addr) __raw_readl(addr) > + > +#define mmio_write16be(val, port) __raw_writew((val), (port)) > +#define mmio_write32be(val, port) __raw_writel((val), (port)) > + > #include <asm-generic/io.h>
This looks correct to me, but there are two points that stick out to me: - why do you only do this for mmio and not for pio? - why do you even use the generic_iomap wrappers rather than the trivial asm-generic versions of those functions? Arnd