Re: [PATCH 04/27] asm-generic: add legacy I/O header files

[Arnd Bergmann]

On Friday 01 May 2009, Alan Cox wrote:
> Joining in late but its not at all highly PC specific. The same frequency
> is used for a whole pile of setups (Alpha etc). It's not well named but
> there are good sound reasons the PC chose 1193182 and while those reasons
> have long lapsed its a good frequency for other reasons nowdays.
> 
> The clock isn't for the PIC either - its for the PIT (although its used
> to clock various other things).
> 
> We actually have a define of PIT_TICK_RATE internal to the x86 port for
> those x86 cases that can use it.

How about this comment then:

/*
 * CLOCK_TICK_RATE is traditionally the base frequency using the PC-style
 * i8253 "PIT" timer. Architecture independent device drivers should not
 * rely on this value.
 * Any architecture that either has a real PC-style PIT, or does not have a
 * fixed timer interval at all and just needs to provide some value here
 * should just fall back to this default.
 */

	Arnd <><
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