Re: [PATCH] m68k: io: Fix io{read,write}{16,32}be() for Coldfire peripherals

[Greg Ungerer]

Hi Angelo,

On 3/6/19 10:26 pm, Angelo Dureghello wrote:
> couldn't seen any follow up on this patch. I tested it and at least
> for mcf5441x it works properly and solves all issues.
>
> Do you think it may be accepted as an initial fix ?

I'll add it to the m68knommu git tree.
Seeing as you wrote it Geert I assume you have no problem with that?  :-)

Regards
Greg


> On Mon, Apr 29, 2019 at 10:19:37AM +0200, Geert Uytterhoeven 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 <angelo@xxxxxxxx>
> > Fixes: aecc787c06f4300f ("iomap: Use non-raw io functions for io{read|write}XXbe")
> > Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> > ---
> > 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>
> >   
> >   #endif /* _M68K_IO_H */
> > --
> > 2.17.1