[U-Boot-Users] PATCH: Introducing CONFIG_BOARD_PRE_RESET

Steven Scholz
2004-10-26T07:06:25Z

Wolfgang Denk wrote:
> In message <417D0D67.2000000@imc-berlin.de> you wrote:
>
>>as mentioned on list before some boards/cpus might need some extra code to be
>>executed _before_ rebooting. E.g. the i.MX hangs when doing "reset" while the
>>LCD controller is still enabled.
>
>
> I remember that we discussed this before, but now that I think about
> this again I changed my mind: I don't think there is a valid reason
> to add this code.
>
>
>>That is why I'd like to introduce CONFIG_BOARD_PRE_RESET and board_pre_reset().
>
>
> No. You write: i.MX hangs when doing "reset". I guess the board does
> not hand if you power cycle it, or if you press the reset button,
> right? So the conclusion is that the reset code does not do what you
> think it does - i. e. it does not cause a reset of the processor.
>
> This is a problem that should be fixed. Once fixed, this patch is not
> needed any more.

Well, it's a bug in the CPU. If the LCDC DMA is running, the cpu won't reboot
with a simple "mov pc, r0".
But then switching off the i.MX LCD controller has to be done in
cpu/arm920t/start.S where reset_cpu() is. And you don't wanna do this. There
already are enough #ifdefs in cpu/arm920t/start.S.

And how about the AT91RM9200(DK) where the author wants to "shutdown the console
to avoid strange chars during reset"???

--
Steven Scholz