Re: am335x: system doesn't reboot after flashing NAND

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On Wed, Jul 2, 2014 at 5:45 PM, Yegor Yefremov
<yegorslists@xxxxxxxxxxxxxx> wrote:
> On Fri, Jun 6, 2014 at 11:33 AM, Roger Quadros <rogerq@xxxxxx> wrote:
>> On 06/05/2014 01:07 PM, Yegor Yefremov wrote:
>>> On Thu, Jun 5, 2014 at 12:02 PM, Roger Quadros <rogerq@xxxxxx> wrote:
>>>> On 06/04/2014 10:45 PM, Yegor Yefremov wrote:
>>>>> On Wed, Jun 4, 2014 at 12:52 PM, Sekhar Nori <nsekhar@xxxxxx> wrote:
>>>>>> On Wednesday 04 June 2014 04:00 PM, Yegor Yefremov wrote:
>>>>>>> On Wed, Jun 4, 2014 at 12:20 PM, Sekhar Nori <nsekhar@xxxxxx> wrote:
>>>>>>>> On Wednesday 04 June 2014 03:11 PM, Yegor Yefremov wrote:
>>>>>>>>> On Wed, Jun 4, 2014 at 10:48 AM, Roger Quadros <rogerq@xxxxxx> wrote:
>>>>>>>>>> Hi,
>>>>>>>>>>
>>>>>>>>>> On 06/04/2014 11:25 AM, Yegor Yefremov wrote:
>>>>>>>>>>> On Wed, Jun 4, 2014 at 8:40 AM, Sekhar Nori <nsekhar@xxxxxx> wrote:
>>>>>>>>>>>> On Tuesday 03 June 2014 04:18 PM, Yegor Yefremov wrote:
>>>>>>>>>>>>> On Tue, Jun 3, 2014 at 9:57 AM, Yegor Yefremov
>>>>>>>>>>>>> <yegorslists@xxxxxxxxxxxxxx> wrote:
>>>>>>>>>>>>>> Kernel: 3.14, 3.15 (I haven't tried another kernels)
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> As soon as I write something to my NAND flash (via cat image >
>>>>>>>>>>>>>> /dev/mtdblockx or ubiupdatevol) and make reboot or press a reset
>>>>>>>>>>>>>> button, I see only CCCCC and nothing happens before I make a power
>>>>>>>>>>>>>> cycle. Any idea?
>>>>>>>>>>>>>
>>>>>>>>>>>>> Just forgot to mention, that I was actually booting from MMC (mmc1).
>>>>>>>>>>>>> The boot sequence is UART0...XIP...MMC0...NAND.
>>>>>>>>>>
>>>>>>>>>> Can you try to get XIP out of the boot sequence and see if it works?
>>>>>>>>>> Maybe try to boot from mmc directly?
>>>>>>>>>>
>>>>>>>>>> This would prove that NAND/GPMC driver is leaving some state that doesn't
>>>>>>>>>> go well with the bootROM XIP.
>>>>>>>>>
>>>>>>>>> This configuration is soldered. It won't be easy to change.
>>>>>>>>
>>>>>>>> Most likely XIP is the issue if sysboot has not changed.
>>>>>>>>
>>>>>>>> The way ROM works for XIP boot is:
>>>>>>>>
>>>>>>>> 1) Set chip select 0 base address to 0x0800'0000
>>>>>>>> 2) Read memory at 0x0800'0000
>>>>>>>> 3) If something else other than 0x0 or ~0x0 is found, jump to
>>>>>>>> 0x0800'0000 and start executing.
>>>>>>>>
>>>>>>>> Can you check to see the contents of 0x0800'0000 before and after nand
>>>>>>>> write using mtdblock?
>>>>>>>
>>>>>>> Before writing:
>>>>>>>
>>>>>>> # devmem 0x08000000 32
>>>>>>> 0xFFFFFFFF
>>>>>>>
>>>>>>> After writing:
>>>>>>>
>>>>>>> # devmem 0x08000000 32
>>>>>>> 0xE0E0E0E0
>>>>>>
>>>>>> Okay, so this is the cause of failure to boot. I am not sure what
>>>>>> operation by NAND driver causes this value to change. Perhaps you could
>>>>>> bisect a bit by dumping this address at various points during the write
>>>>>> operation?
>>>>>>
>>>>>> If you have a debugger it will become easy to do this.
>>>>>
>>>>> The 0x80000000 address seems to be the beginning of NAND region:
>>>>>
>>>>> ranges = <0 0 0x08000000 0x10000000>;   /* CS0: NAND */
>>>>>
>>>>> I've taken this example from am335x_evm.dts. I have tried to change
>>>>> the mapping to 0x90000000, but kernel still uses 0x80000000, Where in
>>>>> the kernel will "ranges" be evaluated? I'm digging thorugh
>>>>> arch/arm/mach-omap2/gpmc.c and gpmc-nand.c, but didn't really found
>>>>> the place.
>>>>
>>>> Well it doesn't. It just uses whatever was setup by the bootloader or
>>>> randomly allocated by gpmc_cs_request().
>>>>
>>>> I'm working on fixing this up. I should be posting v2 of the GPMC refactor
>>>> series by this week and you should be able to map the CS region as specified
>>>> in the DT.
>>>>
>>>> Till then, maybe you can pre-configure CS0 in the bootloader to wherever you want
>>>> or alternatively call gpmc_cs_remap() after the gpmc_cs_request() in gpmc_nand_init();
>>>
>>> I've found the stuff in bootloader and mapped NAND to 0x09000000, but
>>> it didn't help.
>>>
>>
>> Not sure why it didn't work. Was the CSVALID bit in GPMC_CONFIG7_0 register set?
>>
>> If you are daring enough ;), you could try out the cleaned up GPMC code where remapping
>> should work. I still need to do some final touches before I can post it to mailing list.
>>
>> git@xxxxxxxxxx:rogerq/linux.git gpmc-3.16-temp
>>
>> There are some subtle changes you need to do to the GPMC/Nand node. e.g. adding compatible_id,
>> 2nd register space and interrupts. For a working example, please see omap3-beagle.dts.
>>
>> And finally you need to enable CONFIG_TI_GPMC, which is a new kernel config option.
>
> Have attached my BDI2000 to the am335x and found out, that ROM boot
> stops at 0x00020084. AFAIK it can be wrong address exception. Need to
> debug further. Unfortunately I cannot use OpenOCD and my Jtagkey
> debugger :-(
>
> Have also tried 3.16-rc3 without using flash and it freezes during
> reboot from time time, but I can reboot via reset button. With 3.15
> and NAND reset button doesn't help.

Btw how can I debug the kernel via JTAG? I've read, that one must
activate JTAG clock or something like this. What is the proper way to
do this in 3.15 - 3.16?

Yegor
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