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=53656383d512...
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:
- 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.
- 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,