On Thursday, July 19, 2012 12:31 PM, Robert Berger wrote:
> On 07/19/2012 09:41 PM, H Hartley Sweeten wrote:
>> Hello all,
>>
>> Does anyone know what the difference is between inb_p and inb?
>>
>> include/asm-generic/io.h has this:
>>
>> #define inb_p(addr) inb(addr)
>> #define inw_p(addr) inw(addr)
>> #define inl_p(addr) inl(addr)
>
> There might be a difference for m32r
>
> arch/m32r/include/asm/io.h:
>
> #define inb_p _inb_p
>
> arch/m32r/platforms/mappi3/io.c:
>
> unsigned char _inb_p(unsigned long port)
> {
> unsigned char v = _inb(port);
> delay();
> return (v);
> }
Ah... it's a system dependent i/o operation with a pause.
The asm-generic implementation just doesn't have the pause.
Thanks,
Hartley
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