Dear Fabio,
In message <caomzo5befs10xvztnigmejmvjylvv+jqdlzyom9k8-g+zi1...@mail.gmail.com>
you wrote:
>
> > I'm sorry, but I fail to understand how writew() can be better than
> > another I/O accessor. Neither of these has the capability to detect
> > the endianess of this specific register interface ?
>
> It's not that writew() is better. The problem is that we cannot use
> clrsetbits_le16() for a big endian controller.
On ARM (a LE architecture), clrsetbits_le16() maps down into:
clrsetbits_le16 ->
out_le16 / in_le16 ->
out_arch, w,le16 / in_arch, w,le16 ->
__raw_writew(cpu_to_le16()) / le16__to_cpu(__raw_readw()) ->
__raw_writew() / __raw_readw()
while
writew() ->
__raw_writew(cpu_to_le16(v),__mem_pci(c))
__raw_writew()
Both map into __raw_writew() [which then boild down into
__arch_putw() which is just a volatile unsigned short write access.
So both clrsetbits_le16() and writew() are little endian accessors.
In which way would one write other data to the device than the other?
Best regards,
Wolfgang Denk
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de
The human race has one really effective weapon, and that is laughter.
- Mark Twain
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