Booting mx25 based device from SD and NOR

[Eric Bénard]

Hi,

Le Thu, 24 May 2012 15:18:13 +0200,
Roberto Nibali <rnibali at gmail.com> a écrit :
> On Thu, May 24, 2012 at 2:58 PM, Eric Bénard <eric at eukrea.com> wrote:
> > Le Thu, 24 May 2012 14:49:36 +0200,
> > Roberto Nibali <rnibali at gmail.com> a écrit :
> > > I haven't found a combination of root/rootfstype yet that permits me to
> > > boot from barebox either from NFS, TFTP, MMC/SD or NOR yet. No matter
> > what
> > > I try, the kernel spits back at me.
> > >
> > well NAND boot + nand rootfs works fine here (cpuimx25) and I assume
> > NAND boot + sd rootfs would work as sd is properly detected during boot.
> >
> > Yep, I believe it's more a question of me setting the parameters correctly
> upon boot. But without a proper low level init (which I don't have because
> I do not really understand all the details of the low level code), there
> are other factors which could inhibit the proper boot, as you mention below.
> 
if your sd's partitions are detected by the kernel you must be able to
boot a rootfs on it it's just a bootargs problem (and kernel
configuration to have the right FS included).
> 
> > > Also I have the problem that my NOR is only detected when using barebox
> > as
> > > a second stage boot loader from uboot. If booting from SD into barebox,
> > the
> > > NOR is not detected. I have added the following changes to figure out
> > > what's going on:
> > >
> > > .../...
> > > What's going on here?
> > >
> > bad iomux and/or bad WEIM configuration
> 
> 
> I support WEIM configuration is done in the low level part, isn't it? Where
> would I find an appropriate example? I have been reading all the fsl
> board's low_level codes, but have a hard time figuring out how to apply it
> to my board.
> 
> With regard to the IOMUX, I was under the impression that it does not
> matter much, since after low level code run, the execution path is:
> 
>         late_initcall()
>         mem_initcall()
>         device_initcall() --> add_cfi_flash_device()
>         console_initcall() --> mxc_iomux_v3_setup_multiple_pads()
>         core_initcall()
> 
> So CFI/NOR detection happens before IOMUX setup, at least that's what I
> have gathered for my board copying from various other examples in barebox.
> What would the correct code execution path be from the architectural point
> of view?
> 
nothing prevents you from moving mxc_iomux_v3_setup_multiple_pads to
device_initcall as done in 
http://git.pengutronix.de/?p=barebox.git;a=blob;f=arch/arm/boards/eukrea_cpuimx25/eukrea_cpuimx25.c;h=1b8f618138023b88893a024ddc0c078b7b9f2325;hb=c48de4beee21c3a5573cec084123c33ae08f6f7a

for the weim setting you may need to do something similar to what is
done on line 187 of :
http://git.pengutronix.de/?p=barebox.git;a=blob;f=arch/arm/boards/eukrea_cpuimx27/eukrea_cpuimx27.c;h=63e87c9551c440edab572f5252a503ba4d533161;hb=c48de4beee21c3a5573cec084123c33ae08f6f7a

Eric