Hi Hans,
On 12/11/2016 11:22, Hans de Goede wrote:
Hi,
On 11-11-16 19:33, Mylene Josserand wrote:
Hi everyone,
I am currently using FEL and Fastboot to flash a sunxi-device with SPL
and u-boot.
In my board, I have two MMC devices: a MMC slot and an eMMC.
My use-case is to flash an empty device. I want to use FEL to boot a
u-boot and then, use fastboot to flash u-boot into eMMC.
When I am using an u-boot via FEL, the eMMC is configured as MMC1. To
be able to flash u-boot on it, I need to set
CONFIG_FASTBOOT_FLASH_MMC_DEV to 1. Thanks to that, the flashboot
command is working fine.
But when I am booting on my fresh u-boot from eMMC, it is now
configured as MMC0 and not MMC1 anymore.
It produces some problems in my case as I configured the
CONFIG_FASTBOOT_FLASH_MMC_DEV to 1 so I can not use fastboot anymore
to flash the eMMC (as, now, fastboot is trying to flash u-boot on my
MMC slot and not my eMMC). This is clearly not what I wanted to. I
would like to use fastboot to flash the same MMC device: eMMC.
This issue is located in this part of the code:
http://git.denx.de/?p=u-boot.git;a=blob;f=board/sunxi/board.c;h=53656383d512199338dcdc1d4fdc4f7f939c9b61;hb=HEAD#l377
Do you know why sunxi boards have this behavior ? Why this MMC
device's swap is implemented ?
Most boards with emmc can boot from either the external mmc slot (sdc0 /
port F)
or the emmc (sdc2 / port C).
Depending on the boot source, we map these as follows in u-boot:
Boot source sdc2:
MMC0: sdc2
MMC1: sdc0
Other boot source (including sdc0):
MMC0: sdc0
MMC1: sdc2
There are a number of reasons for this:
1) The loading of u-boot proper (the 3th boot stage) by the SPL (the 2nd
boot stage,
with the SoCs BootROM being the 1st stage), the SPL mmc code used to
always load from
MMC0, I believe this has been fixed now, so this is mainly historical.
2) The standard bootscripts from u-boot/include/config_distro_bootcmd.h
start by
looking for extlinux/extlinux.conf / boot.scr in MMC0, clearly if we
booted from sdc2,
the first place to look for these files should be sdc2, and not some
random non-bootable
sdcard in the external slot. As is explained in the comment above the
code for this you
already found.
Thank you for the explanations. I understand it better.
I would certainly welcome some patches where some early init code would
set a bootdev
environment variable and modify the boot_targets env variable to do the
swapping there,
but include/config_distro_bootcmd.h does not make this easy. The best
solution I can come
up with would be something like the attached patch.
I'm not 100% sure that the "if test ${bootdev} = sdc2;" bit will work,
as I'm not sure
if the u-boot build-in "test" command supports comparing strings. Other
then that
you would need to add some code to set bootdev in the env based on the
return value
of readb(SPL_ADDR + 0x28), or maybe a more generic helper function using
the standardized
return value from spl_boot_device(), as that may be useful for other
boards too.
Once you're setting bootdev in the environement correctly, my patch
should do the
trick to try and boot from sdc2 first when booting from the eMMC with
the swapping
code you pointed out removed.
Then we can simply always map the devices as:
MMC0: sdc0
MMC1: sdc2
and we would still try to load extlinux/extlinux.conf from sdc2 first if
that is the
boot source.
Thank you very much for the details about how it can be handled. I will
have a try and, of course, send patches if I make it work !
If you can get this to work then I would be happy to merge this, note the
include/config_distro_bootcmd.h bit should be submitted upstream as a
separate
patch.
Noted. I made also some modifications to make fastboot/GPT partitions
working with sunxi devices so I will send patches about that, soon.
Best regards,
--
Mylène Josserand, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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