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

[aneesh.bansal at freescale.com]

> -----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.

Aneesh