Porting barebox to Novena: misc questions

[Sascha Hauer]

Hi Sean,

On Thu, Mar 13, 2014 at 10:04:35AM +0800, Sean Cross wrote:
> Hi,
> 
> I've finally managed to get U-Boot's SPL to configure DDR3 and load
> barebox off of a FAT partition on an i.MX6DL.  I also have a barebox
> build with most features turned on, and I'm running into a number of
> problems.  barebox is able to load a zImage off of the FAT partition,
> set up ATAGs, and jump to it.  So I have the basics done.  But there are
> lots of little things that aren't working.
> 
> When I boot without an Ethernet cable plugged in, the "timeout" command
> takes a very long time to complete.  It generally freezes at "Hit any
> key to stop autoboot:  3" and tends to ignore input for around ten
> seconds.  How can I prevent this from happening, short of compiling out
> FEC support?

Are you trying to start from network without a cable plugged in? When I
start from network without a cable I get:

running /env/bin/init...

Hit m for menu or any other key to stop autoboot:  1
blspec: blspec_scan_directory: net loader/entries
booting net
dhcp failed: Network is down
dhcp: Network is down

It indeed takes some seconds until we are sure that the link is down.
That timeout could be reduced, but we must give the phy some time to
bring up the link.

Or does this happen when you are not trying to boot from network at all?
That shouldn't happen. If it does, maybe some automount command triggers
network accesses.

> 
> The "usb" command just hangs the system.  It should at least detect the
> other ASIX Ethernet port.  I have &usbh1 configured identically to
> sabrelite.  Is there something else I need to configure?

This usually means the phys are not configured correctly. Are you
probing from devicetree?

> 
> The "usbserial" command returns "usbserial: No such device".  Like usb,
> I have &usbotg configured the same as sabrelite.  It doesn't work with
> dr_mode set to either "host" or "otg".

Ok, from devicetree it seems. I can say that there shouldn't be any bugs
in the common usb code preventing your devices from being probed. It
normally boils down to some usbmisc register setting being wrong.

> 
> How can I pass the correct ram size to Linux?  The comment on
> barebox_arm_entry() notes that "[memsize] doesn't necessarily have to be
> the full SDRAM", and indeed I notice that barebox hangs if I pass it the
> full 3840 MB passed from U-Boot.  So I'm currently limiting it to 1GB in
> my start_imx6dl_kosagi_novena_6dl routine.  Do I need to somehow add the
> remainder as another bank somewhere?  Or modify the bank size in my
> kosagi_novena_init() in board.c?

If you probe from devicetree the correct amount of memory is taken from
there. If that doesn't work (dynamic amount of memory for example) you
can set the memory in the devicetree to 0 and call arm_add_mem_device
instead.

> 
> Finally, I was unable to get barebox to boot with MMU support.  For some
> reason it kept trying to allocate memory just outside of allocated RAM.

This is related to the wrong memory setup. That should be solved when
you get that straight.

>  Is there any benefit to running with the MMU enabled on i.MX6?

Definitely, yes. barebox runs much faster with MMU enabled.

Sascha

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