Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops

Hi!

modern CPU compared to the bus. But the delay really needs to be something
that is about IO port speed. Ok in theory you could try to measure
a outb using RDTSC and then use udelay, but first you would need

You don't need to. Port 0x80 historically is about 8uS so just udelay(8)
and make sure the initial default delay is conservative enough before the
CPU speed is computed.

0x80 should be fine for anything PC compatible anyway, its specifically
reserved as a debug port and supported for *exactly* that purpose by
many chipsets.

Actually, I've seen few pci cards with leds on port 0x80, and I
wonder: is our outb_p really correct?

I mean, we expect 8usec delay -- historical ISA timing -- but when
_PCI_ card with leds is inserted, it is likely to be faster than old
ISA, right?
Pavel
--
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