Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH] asm-generic/io.h: Fix io{read,write}{16,32}be for big endian systems | Date | Tue, 18 Jan 2011 19:44:07 +0100 |
| |
On Tuesday 18 January 2011 19:11:01 Lars-Peter Clausen wrote: > Currently io{read,write}{16,32} expand to > *addr = cpu_to_leXX(cpu_to_beXX(val)) > and > val = beXX_to_cpu(leXX_to_cpu(*addr)) > > While it should rather be: > *addr = cpu_to_be{16,32}(val) > and > val = be{16,32}_to_cpu(*addr) > > The current implementation works on litte-endian targets(where cpu_to_leXX is a > noop), but breaks on on big-endian targets, this patch fixes it. > > Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
The existing code looks broken on big-endian indeed, thanks for the report!
However, you cannot use __raw_readl in general, because that function knows nothing about the various kinds of I/O accesses (potentially) handled by readl. Think of architectures where readl is not a pointer dereference but something else.
The right solution is probably to use swab16/swab32 for the big-endian functions. This also corrects the iowrite functions which really should be using cpu_to_be32 instead of be32_to_cpu (although they are always defined to be the same afaict.
Arnd
| |