[U-Boot-Users] PATCH: Introducing CONFIG_BOARD_PRE_RESET

[Steven Scholz]

Wolfgang Denk wrote:
> In message <417D0D67.2000000 at 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