Re: Linux Post codes during runtime, possibly OT

Jamie Lokier
2001-01-26T15:31:59Z

Mark Hahn wrote:
> > #ifdef SLOW_IO_BY_JUMPING
> > #define __SLOW_DOWN_IO "\njmp 1f\n1:\tjmp 1f\n1:"
> > #else
> > -#define __SLOW_DOWN_IO "\noutb %%al,$0x80"
> > +#define __SLOW_DOWN_IO "\noutb %%al,$0x19"
>
> this is nutty: why can't udelay be used here? empirical measurements
> in the thread show the delay is O(2us).

Does anyone remember where __SLOW_DOWN_IO is needed any more?

udelay() makes sense. Modern drivers use small udelays themselves to
confirm to chip specs.

Some ISA drivers appear to use outb_p "just to be on the safe side", no
idea if it's appropriate or not. Some even mix outb and outb_p based on
educated guesses. I know, I've written such code :-)

-- Jamie