Re: [PATCH 3/5] powerpc/mpc5121: shared DIU framebuffer support

[Timur Tabi <timur.tabi@gmail.com>]

On Fri, Apr 30, 2010 at 11:22 AM, Scott Wood <scottwood@freescale.com> wrot=
e:

>> That's what I meant. =A0Actually, I think it's ULL. =A0Regardless, I thi=
nk
>> the compiler will see the =A0"1000000000 ... * 1000" and just combine
>> them together. =A0You're not actually outsmarting the compiler.
>
> The compiler will do no such thing. =A0That's a valid transformation when
> doing pure math, but not when working with integers.

I ran some tests, and it appears you're right.  I doesn't make a lot
of sense to me, but whatever.

However, "(1000000000 / pixclock) * 1000" produces a result that's
less accurate than "1000000000000ULL / pixclock".  Unfortunately, that
math caused a linker problem with __udivdi3 when I tried it, so maybe
you can use do_div() instead?

>> =A0 =A0 err =3D -1;
>>
>> because he wanted it to be the largest possible integer.
>
> -1 is not the largest possible integer. =A0LONG_MAX, perhaps?

What, you don't like implicit casting of -1 to an unsigned? :-)

Since err is a long integer, LONG_MAX is the better choice.

--=20
Timur Tabi
Linux kernel developer at Freescale