AT91RM9200 hang in atmel_serial_putc

[Peter Kardos]

Hi Sascha,

I've tested your workaround and it seems to work; the board starts and 
attempts
to boot.

Peter

On 8/22/2016 11:00 AM, Peter Kardos wrote:
> During the weekend I've played with this some more...
> It seems that the "breakage" was introduced with v2016.05. This version
> introduced the "exception vector remapping to 0xFFFF*".
> Unfortunately AT91RM9200 has peripherals in this region.
>
> I'll test the patch tonight when i get home.
>
> Peter
>
> On 2016-08-22 08:10, Sascha Hauer wrote:
>> On Thu, Aug 18, 2016 at 11:15:33PM +0200, Peter Kardos wrote:
>>> Hi Sascha,
>>>
>>> I may have something. It seems the memory (MMU?) gets "messed" up;
>>>
>>> Reading the debug uart registers (v2015.07) gives reasonable 
>>> results, like
>>>      (gdb) x/32w 0xfffff200
>>>      0xfffff200:    0x00000000    0x00000800    0x00000000 0x00000000
>>>      0xfffff210:    0x00000000    0x40001a1a    0x00000000 0x00000000
>>>      0xfffff220:    0x00000021    0x00000000    0x00000000 0x00000000
>>>      0xfffff230:    0x00000000    0x00000000    0x00000000 0x00000000
>>>      0xfffff240:    0x09290781    0x00000000    0x00000000 0x00000000
>>>
>>> However the content from v2016.08 gives
>>>
>>> 0xFFFFF200    D78D7E1F    F1139ADE    413E0FE5    BBFB6DF2
>>> 0xFFFFF210    7D78666E    79CBDEA6    8FB2CB03    BEF6C2B7
>>> 0xFFFFF220    C9071D17    FA1EFA2D    C4BCD95E    27D73C7C
>>> 0xFFFFF230    727C3437    DFBDEBED    69C45C2A    7F5958F6
>>> 0xFFFFF240    834B237E    F8B8A211    1AC74D66    FAE06274
>> Uh, this indeed seems to be messed up by the MMU, more specifically
>> during setup of the vector table. Could you try the attached patch?
>> It's not a solution, but is a clear indication that the bug is in this
>> area.
>>
>> Sascha
>>
>> ---------------------------8<--------------------------------
>>
>>  From eb66f09db694a0bc1fc88cde8d86e47faf6debf9 Mon Sep 17 00:00:00 2001
>> From: Sascha Hauer <s.hauer at pengutronix.de>
>> Date: Mon, 22 Aug 2016 08:05:38 +0200
>> Subject: [PATCH] ARM: Disable vector table (tmp)
>>
>> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
>> ---
>>   arch/arm/cpu/mmu.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/arch/arm/cpu/mmu.c b/arch/arm/cpu/mmu.c
>> index a31bce4..fc26077 100644
>> --- a/arch/arm/cpu/mmu.c
>> +++ b/arch/arm/cpu/mmu.c
>> @@ -289,6 +289,8 @@ static void create_vector_table(unsigned long adr)
>>       u32 *exc;
>>       int idx;
>>   +    return;
>> +
>>       vectors_sdram = request_sdram_region("vector table", adr, SZ_4K);
>>       if (vectors_sdram) {
>>           /*
>