Re: [PATCH] atp870u: Split long udelay()

[Ben Hutchings <ben@decadent.org.uk>]

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On Fri, 2010-02-19 at 16:44 +0000, Ben Hutchings wrote:
> On Fri, Feb 19, 2010 at 09:28:19AM -0600, James Bottomley wrote:
> > On Fri, 2010-02-19 at 01:56 +0000, Ben Hutchings wrote:
> > > udelay() is supposed to be limited to 1 ms, and will generate a
> > > __bad_udelay() on ARM for constant arguments > 2000.  Split
> > > udelay(0x800) into mdelay(2); udelay(48).  (I suspect that msleep(3)
> > > would work but I do not know how critical the timing is here.)
> > 
> > So no to this one.  Either ARM is right and udelay > 2000 is wrong
> > (which actually sounds correct given how long this will eat CPU for) so
> > the driver needs fixing, or ARM is wrong and the warning needs fixing.
> > 
> > Splitting the delay to defeat the warning while retaining the behaviour
> > it was trying to warn about is the wrong thing to do.
>  
> AIUI the restrictions on udelay() are there because the delay is likely
> to be inaccurate for large arguments.  If it was actually wrong to wait
> for over a millisecond then mdelay() would not exist.

Please could you respond to the above?

Ben.

-- 
Ben Hutchings
Horngren's Observation:
                   Among economists, the real world is often a special case.

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