Re: [Gumstix-users] devmem2 issues with overo kernel

[Alex S. <kin...@gm...>]

>From the Revs you've tried it sounds like the "problem" cropped up wither
from the R40 to R41 commit, or the R41 to R42 commit. You might try backing
to R41. If that fails concentrate on a diff between R40 and R41. If it
works, then focus on R41 to R42. It may be painful but one way you could go
about it is to do a GIT diff between R42 and R41 and see what changed (or
R41 and R40 depending on if R41 works or not)... I imagine it is a lot of
changes to sift through, however you may be able to limit your scope to the
memory management files (mm folder). Second alternative is to read the
commit log for that diff. Might also check the gumstix hardware files to see
if any platform drivers have remapped your timer registers to elsewhere...

Best Regards,
-Alex Stewart

On Fri, Jan 8, 2010 at 3:42 PM, Frank Agius <ft...@ya...> wrote:

> I am using an overo earth COM board.  With the latest kernel built with
> OE, linux-omap3-2.6.31-r50, writes to certain memory address with
> devmem2 fail:
>
>  bash-3.2# devmem2 0x48088024 w 0x00000000
>  /dev/mem opened.Unhandled fault: external abort on non-linefetch
> (0x1018) at 0x4
>  Memory mapped at address 0x40020000.
>  Bus error
>
> The address 0x48088024 is one of timer registers (gp timer 11 TCLR) and
> should be valid. With some previous versions of the kernel, devmem2
> worked properly.  I backtracked and found that with the kernel from
> linux-omap3-2.6.30-r40, devmem2 for address 0x48088024 works, but with
> the kernel from linux-omap3-2.6.30-r42 and beyond, devmem2 fails as
> above.  How can I determine the changes between linux-omap3-2.6.30-r40
> and linux-omap3-2.6.30-r42? Any other debug tips are welcome.
>
> frank
>
>
>
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