[U-Boot] mcf5307, timer 2 issue loading linux

[angelo <angelo70@gmail.com>]

Hi all,

finally this is what seems to happen:

1. U-boot setup timer 2 using LEVEL 7 autovectored interrupt. For this case
the uClinux " movew   #0x2700, %sr " in head.S don't disable the timer 
interrupt.
2. execution of uClinux proceed into head.S, rewriting %a7 (%sp) just 
after writing
%sr.
3. at a certain (probably variable) moment, timer interrupt happen, and 
since the
stack pointer is no more valid, it seems to get stucked and can't return 
correctly.

Solution (temporary, RFC)
uBoot command bootm allows an "arch_preboot_os()":

cmd_bootm.c

case BOOTM_STATE_OS_GO:
          disable_interrupts();
          arch_preboot_os();
          boot_fn(BOOTM_STATE_OS_GO, argc, argv, &images);
          break;

I used it to disable LEVEL7 interrupt. Next os loading works.

NOTE: For this issue using command "go" is not possible, since it is not 
meant for os loading,
and don't do any arch_preboot_os(); .

What i still don't understand is why this issue is not happening on 
other coldfire models that have
UBoot and uClinux. Probably they are faster, and head.S can be processed 
and timers re-initialized before interrupt occours.

Let me know your thoughts.

Regards,
angelo


On 03/08/2011 14:50, Greg Ungerer wrote:
> Hi Angelo,
>
> On 08/03/2011 06:09 PM, angelo wrote:
>> i am reporting the following issue, maybe related to something wrong in
>> my new mcf5307 support addition (still under testing), or maybe not:
>>
>>
>> 1. U-Boot run correctly, timer2 is enabled as a system timestamp 
>> counter.
>> 2. I load a uClinux bianry from flash to SDRAM with  "cp.l FLASH_ADDR
>> SDRAM_ADDR SIZE/4
>> 3. i launch the binary with "go SDRAM_ADDR"
>>
>> First startup of linux (head.S) is locked, since U-boot timer2 interrupt
>> happen, exactly while linux startup (in head.S) is moving ROMFS inside
>> sdram.
>> After the interrupt happen, i was assuming it return correctly allowing
>> linux to load, but execution is locked inside this ROMFS copy of head.S.
>>
>> Disabling the timer2 init in board.c, linux is loaded as expected.
>>
>> Shouldn't timer2 be disabled for al coldfire models before loading 
>> linux ?
>
> What interrupt level is timer2 set to?
>
> The second instruction into running uClinux is:
>
>     movew   #0x2700, %sr
>
> which will disable all interrupts - excepting anything set to the
> non-maskable level 7.
>
> Regards
> Greg
>
>
> ------------------------------------------------------------------------
> Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
> SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
> 8 Gardner Close,                            FAX:         +61 7 3891 3630
> Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com


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