[U-Boot] [PATCH 1/3] powerpc/p1010rdb: SECURE BOOT- define CONFIG_SYS_RAMBOOT for NAND boot

[York Sun <yorksun@freescale.com>]

On 03/10/2014 04:58 PM, Scott Wood wrote:
> On Mon, 2014-03-10 at 04:14 -0500, Bansal Aneesh-B39320 wrote:
>>> -----Original Message-----
>>> From: Sun York-R58495
>>> Sent: Saturday, March 08, 2014 12:31 AM
>>> To: Bansal Aneesh-B39320
>>> Cc: Wood Scott-B07421; Wolfgang Denk; u-boot at lists.denx.de; Gupta
>>> Ruchika-R66431
>>> Subject: Re: [U-Boot] [PATCH 1/3] powerpc/p1010rdb: SECURE BOOT-
>>> define CONFIG_SYS_RAMBOOT for NAND boot
>>>
>>> On 03/07/2014 10:57 AM, Scott Wood wrote:
>>>> On Thu, 2014-03-06 at 03:24 -0600, Bansal Aneesh-B39320 wrote:
>>>>>> -----Original Message-----
>>>>>> From: Wood Scott-B07421
>>>>>> Sent: Wednesday, March 05, 2014 11:30 PM
>>>>>> To: Bansal Aneesh-B39320
>>>>>> Cc: Sun York-R58495; Wolfgang Denk; u-boot at lists.denx.de; Gupta
>>>>>> Ruchika-R66431
>>>>>> Subject: Re: [U-Boot] [PATCH 1/3] powerpc/p1010rdb: SECURE BOOT-
>>>>>> define CONFIG_SYS_RAMBOOT for NAND boot
>>>>>>
>>>>>> On Tue, 2014-03-04 at 23:30 -0600, Bansal Aneesh-B39320 wrote:
>>>>>>> Yes, in case of secure boot from NAND, the DRAM is initialized by
>>>>>> the
>>>>>>> BootROM and complete u-boot image is copied from NAND to DRAM by
>>>>>>> the
>>>>>> BootROM.
>>>>>>> So, it should be called RAMBOOT.
>>>>>>
>>>>>> DRAM or SRAM?  Having ROM initialize DDR is a bit scary.
>>>>>>
>>>>>> -Scott
>>>>>>
>>>>> It can be either DDR or SRAM. It is not hardcoded in BootROM to
>>> initialize DDR.
>>>>> This depends on the config words (CF_WORDS) in the CF_HEADER.
>>>>> The Boot ROM code parses the config words and programs the
>>> addresses
>>>>> with data values accordingly. The user may opt to initialize DDR
>>> and
>>>>> get the image copied onto DDR or configure CPC as SRAM and get the
>>> Image copied onto SRAM.
>>>>> On 1010,
>>>>
>>>> P1010?  LS1010?  Something else?
>>>>
>>>>> the CPC size is not big enough to accommodate the U-boot image.
>>>>> So, currently the CF_WORDS are for DDR to be initialized and copy
>>> the image on DDR.
>>>>
>>>> Generally if SPD is present, it should be used to init DDR rather
>>> than
>>>> using hardcoded values.  If U-Boot doesn't fit in SRAM, you can use
>>>> SPL instead of hardcoded init.
>>>
>>> I agree with Scott on this point. Using hardcoded values totally skip
>>> DDR driver. You don't only lose the flexibility of various speeds, you
>>> also skip all workarounds implemented in DDR driver.
>>>
>>> York
>>
>> Currently we are following the same approach which was there for SPI
>> and SD on P1010 i.e hardcoded initialization of DDR in platforms like
>> P1010, 9131/9132 using config words.
> 
> I don't know about 9131/9132, but on P1010RDB we now use SPL to init DDR
> when booting from SPI/SD.
> 
> In any case, "we've always done it this way" isn't really a good reason.
> 

We should move to SPL for SD/SPI/NAND. Let's take step by step. I intend to
accept the updated patch to get NAND SECURE boot working for this board. Aneesh
will submit patches to move to SPL, for SD/SPI/NAND.

York