[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 02:14 AM, 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.
> 

Understood.

York