mcf5307, timer 2 issue loading linux

Hi all,

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 ?

Every help is appreciated.

reagrds,
angelo

Hi Angelo,

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

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

  .:.:.SYSAM.:.:.

   di Angelo Dureghello
     via San Nazario 149
       34151, Trieste, Italy
     ++39 340 7631990
   www.sysam.it  <http://www.sysam.it>


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Dear angelo,

You must not start Linux with a "go" command. Please use "bootm" for this purpose (and then you also don;t have to copy the kernal manually).

Best regards,

Wolfgang Denk

DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
In the beginning, I was made. I didn't ask to be made. No one consul-
ted with me or considered my feelings  in  this  matter.  But  if  it
brought  some  passing fancy to some lowly humans as they haphazardly
pranced their way through life's mournful jungle, then so be it.
- Marvin the Paranoid Android

Hi Wolfgang,

i confirm that before the patch/solution applied (i just posted it), i also tried "bootm FLASH_ADDR". Same result, loading fail, since timer2 interrupt is not stopped and the interrupt happen just after the linux head.S execution.

As i said, probably this issue was not visible in other coldfire models since mcf5307 run at 90mhz only.

I have copied the "arch_preboot_os()" solution from other boards, that was doing the same thing, disabling async interrupts before loading the os.

Regards,
angelo

  .:.:.SYSAM.:.:.

   di Angelo Dureghello
     via San Nazario 149
       34151, Trieste, Italy
     ++39 340 7631990
   www.sysam.it  <http://www.sysam.it>


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