Re: [PATCH v4] introduce macro spin_event_timeout()

[Will Newton]

On Tue, Mar 10, 2009 at 3:50 PM, Timur Tabi <timur@xxxxxxxxxxxxx> wrote:
> Alan Cox wrote:
>
>> NAK this - on a lot of platforms 1uS is the wrong timescale. Also we
>> shouldn't be encouraging this kind of polling by making it very easy to
>> write.
>
> Well, I can agree that the time scale might be wrong on some platforms.
>  The original version of spin_event_timeout() used jiffies, but some
> people said that a jiffy is too long of a timescale, so I changed it to
> udelay.

The correct timescale is rather application dependant - for some
accesses that cross clock domains it can be a requirement to wait for
a small number of core clock cycles (2 - 20) for a condition to become
true, for others, e.g. PIO, it is more appropriate to wait for a few
100 cycles.
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