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H. Peter Anvin wrote: > David Newall wrote:>> Where did the 8us delay come from? The documentation and source is >> careful not to say how long the delay is. Would changing it to, say >> 1us, be technically wrong? Is code that requires 8us correct?>> I think a single ISA bus transaction is 1 µs, so two of them back to > back should be 2 µs, not 8 µs... Exactly. You think it's 2us, but the documentation doesn't say. The _p functions are generic inasmuch as they provide an unspecified delay. Drivers which work across platforms, and which use _p, therefore have different delays on different platforms. Should the length of the delay be unimportant? I wouldn't have thought so. If it is important, does that mean that such drivers are buggy on some platforms? I really *hate* the idea that access to non-present hardware is used to generate a delay. That sucks so badly. It's worthy of a school-aged hacker, not of a world-leading operating system. It's so not best-practice that it's worst-practice. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||
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