[U-Boot] oamp3: bug in clock.c with gcc 4.5.1?

[Wolfgang Denk]

Dear Alexander,

in message <4D0B6D1F.8010304 at ahsoftware.de> you wrote:
> 
> I think I've nailed down, why an u-boot compiled with gcc 4.5.1 fails 
> here. Compiling arch/arm/cpu/armv7/omap3/clock.c with
> ...
> That means get_sys_clk_speed() will allways return S12M, at least that 
> is what I'm reading here. And I don't see why gcc should be allowed to 
> optimize that cdiff to a fixed value and therefor returning only S12M.

Well, if you look at the code after preprocessing it looks like this:

struct gptimer *gpt1_base = (struct gptimer *)0x48318000;
...
cstart = (*(volatile unsigned int *)(&gpt1_base->tcrr));
...
cend = (*(volatile unsigned int *)(&gpt1_base->tcrr));
cdiff = cend - cstart;


Eventually that simple definition of readl() is no longer good enough
for recent compilers.  There is probably a very good reason that Linux
uses a "__iormb();" memory barrier in the definition of readl() and
similar macros.

We should probably update "arch/arm/include/asm/io.h" ...

But then, I'm not an expert for ARM.



Best regards,

Wolfgang Denk

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