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

[Scott Wood]

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.

-Scott