Re: [PATCH] devicetree: pull evaluation of of_address_to_resource() out of loop in of_dev_lookup()

[Lothar WaÃmann]

Hi,

Grant Likely writes:
> On Tue,  3 Apr 2012 14:48:28 +0200, Lothar WaÃmann <LW@xxxxxxxxxxxxxxxxxxx> wrote:
> > The result of_address_to_resource(np, 0, &res) is independent from the
> > for (; lookup->compatible != NULL; lookup++) {
> > }
> > loop evaluation. Evaluate it once before entering the loop.
> > 
> > Also add a space between 'for' keyword and parens.
> > 
> > Signed-off-by: Lothar WaÃmann <LW@xxxxxxxxxxxxxxxxxxx>
> > ---
> 
> What is the reason for this patch?  The error path may be slightly
> less efficient in the failure case, but it isn't incorrect.
> 
What's not correct? If of_address_to_resource() yields a non-zero
result, the function will never reach the 'return lookup' inside the
loop but only the 'return NULL' at the end of the function. Thus it is
vain to re-evaluate of_address_to_resource() in every loop.


Lothar WaÃmann
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