[U-Boot] [PATCH] sc520: fix build warning about unused temp var

Graeme Russ graeme.russ at gmail.com
Mon Mar 5 23:31:43 CET 2012

Hi Mike,

On Tue, Mar 6, 2012 at 8:55 AM, Mike Frysinger <vapier at gentoo.org> wrote:
> Building the eNET_SRAM board fails for me:
>        sc520_timer.c: In function 'sc520_udelay':
>        sc520_timer.c:81:7: error: variable 'temp' set but not used
>                [-Werror=unused-but-set-variable]
>        cc1: all warnings being treated as errors
>        make[1]: *** [sc520_timer.o] Error 1
> Signed-off-by: Mike Frysinger <vapier at gentoo.org>
> ---
>  arch/x86/cpu/sc520/sc520_timer.c |    5 ++---
>  1 files changed, 2 insertions(+), 3 deletions(-)
> diff --git a/arch/x86/cpu/sc520/sc520_timer.c b/arch/x86/cpu/sc520/sc520_timer.c
> index 495a694..41f121f 100644
> --- a/arch/x86/cpu/sc520/sc520_timer.c
> +++ b/arch/x86/cpu/sc520/sc520_timer.c
> @@ -78,10 +78,9 @@ void sc520_udelay(unsigned long usec)
>  {
>        int m = 0;
>        long u;
> -       long temp;
> -       temp = readw(&sc520_mmcr->swtmrmilli);
> -       temp = readw(&sc520_mmcr->swtmrmicro);
> +       readw(&sc520_mmcr->swtmrmilli);
> +       readw(&sc520_mmcr->swtmrmicro);
>        do {
>                m += readw(&sc520_mmcr->swtmrmilli);

I really appreciate the effort you (and others) have put into fixing this
and I really should have made a more formal response earlier (sorry), but
here goes...

Although this will fix the build warning, the actual implementation of
sc520_udelay is wrong and can produce a timeout which is up to 1000us
short (which I think we can all agree is a bad thing). On top of this,
there is an sc520 silicon bug which means even a technically correct
software implementation may produce erroneous results (although from
memory that produces a timeout which could be 1000us long which is
better than a short timeout)

And then there is the fact that this is a depricated platform - There is
only one physical sc520 board which U-Boot has ever been loaded onto and
that is buried on a shelf in my study somewhere - I'm working on another
x86 board at the moment, but I'm not at liberty to release the code yet.
As soon as that is released, I'm going to remove the sc520 anyway

So do I apply this to fix the build warning knowing there is another more
serious bug and knowing this arch is getting scrapped soon, or do I just
leave it as is?



More information about the U-Boot mailing list