[U-Boot] [PATCH 2/6] nand: Add SPL_NAND support to mxc_nand_spl

[Benoît Thébaudeau]

Hi Philip,

On Friday, April 19, 2013 5:09:59 PM,Philip Paeps wrote:
> On 2013-04-19 16:48:42 (+0200), Philip Paeps <philip at paeps.cx> wrote:
> > On 2013-04-19 15:00:13 (+0200), Philip Paeps <philip at paeps.cx> wrote:
> > > On 2013-04-19 06:10:51 (+0200), Marek Vasut <marex at denx.de> wrote:
> > > > To avoid the old function which are used with the nand_spl/ stuff
> > > > getting in the way of NAND SPL framework, the macro
> > > > CONFIG_SPL_NAND_LEGACY was introduced and two remaining legacy
> > > > boards were adjusted. These board need to be either fixed or
> > > > removed in the long run, but I don't have either.
> > > 
> > > It sounds like "fixing" these boards is mainly a matter of confirming
> > > that a configuration for them based around CONFIG_SPL_FRAMEWORK will fit
> > > in 2K.  If so, I don't think there is any reason to keep legacy support
> > > around.
> > 
> > A first build with CONFIG_SPL_FRAMEWORK came out to nearly 4K.  Large
> > contributors being (unsurprisingly) libcommon and libgeneric.  I had to
> > get rid of a puts() in libspl to make it build without those libraries.
> > Unfortunately, that still came out to 2.2K.  Close. :-)
> > 
> > I couldn't identify any obvious 100 bytes to scrap from glancing at
> > u-boot-spl.map or objdump -D u-boot-spl, but I'll take a look.
> 
> Just as I hit 'send', it occurred to me that this configuration is with
> a fairly lengthy lowlevel_init.S to support external boot.  Paring that
> to the bare minimum gives a u-boot-spl.bin of 1821 bytes.

But this requires a board-specific lowlevel_init() and a hack for puts() (which
is perhaps already solved by Andreas' series), just to bloat the SPL with
stuff useless for those boards, vs. a simple nand_boot() that can be made common
to all SPLs with size restrictions.

> I'm not familiar enough with 'internal boot' and the 'imximage' format
> to judge whether this leaves enough margin for telling the ROM loader to
> do its thing usefully.  Benoît: do you have an idea how long a typically
> useful imximage preamble gets?  Is ~230 bytes sufficient margin?

What do you mean? mx31pdk and tx25, contrary to m53evk, use external NAND boot,
hence the 2-kiB SPL size limit (which could actually be extended to 4 kiB for
tx25, but not for mx31pdk), and they don't require any imximage.

Best regards,
Benoît