U-Boot gets stuck at boot from MMC

Discussion about U-Boot and the kernel.

U-Boot gets stuck at boot from MMC

Postby Rethfor » Sun Aug 29, 2021 6:04 pm

Hi everybody, first I must say I'm a very beginner at subjects like bootloaders. There is a SOM variscite card (VAR-SOM-MX7) that I need to flash the latest Debian. I followed the official tutorial at https://variwiki.com/index.php?title=Debian_Build_Release&release=RELEASE_BUSTER_V1.2_VAR-SOM-MX7 and used a micro SD card for boot process (The SOM is on a custom carrier btw). Prepared SD card successfully but when I boot the SOM from SD card U-Boot just freeze at step as I show below. I couldn't find any solution on the Internet so I'd appreciate any help.
Screenshot from 2021-08-29 18-14-55.png
Screenshot from 2021-08-29 18-14-55.png (41.11 KiB) Viewed 8309 times
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Re: U-Boot gets stuck at boot from MMC

Postby summers » Mon Aug 30, 2021 9:09 am

This sounds like a Debian problem, rather than an Arch one.

Anyway, interrupt the boot loader, and type commands by hand - and see whats wrong. "help" is usually the command to start with ...
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Re: U-Boot gets stuck at boot from MMC

Postby Rethfor » Mon Aug 30, 2021 9:26 am

$this->bbcode_second_pass_quote('summers', 'T')his sounds like a Debian problem, rather than an Arch one.

Anyway, interrupt the boot loader, and type commands by hand - and see whats wrong. "help" is usually the command to start with ...

I can't even get to point where I can interrupt the boot loader, it just hangs there. I think maybe this is because U-Boot doesn't select the right mmc to initialize (like I showed before, it says trying to boot from mmc1 but SD card is on mmc0) but I don't know how can I change this, any idea?
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Re: U-Boot gets stuck at boot from MMC

Postby summers » Mon Aug 30, 2021 10:59 am

Usually uboot has delays built into it - hitting any key them drops you into the boot loader command line.

Usually hammering the space key during boot will do it. This should be before the mmc are scanned etc ...
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Re: U-Boot gets stuck at boot from MMC

Postby Rethfor » Mon Aug 30, 2021 11:26 am

$this->bbcode_second_pass_quote('summers', 'U')sually uboot has delays built into it - hitting any key them drops you into the boot loader command line.

Usually hammering the space key during boot will do it. This should be before the mmc are scanned etc ...

Okay, I'll try when I get on it. Thank you for your reply, I'll update here
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Re: U-Boot gets stuck at boot from MMC

Postby Rethfor » Tue Aug 31, 2021 7:15 am

It doesn't get interrupted and give me the ability to write commands unfortunately. Does anyone have an idea about that, maybe about how can I change the MMC initialization of U-boot?
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Re: U-Boot gets stuck at boot from MMC

Postby summers » Tue Aug 31, 2021 9:02 am

In your uboot defconfig file set the CONFIG_BOOTDELAY variable, e.g. in a file like: https://source.denx.de/u-boot/u-boot/-/tree/master/configs/pico-imx7d_defconfig set $this->bbcode_second_pass_code('', 'CONFIG_BOOTDELAY=5'). Then recompile and reflash. That will give a 5 second delay when you can interrupt uboot - and so type commands and see what is wrong. Also not that that file sets the BOOTCOMMAND so you can see what is run at boot time ...
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Re: U-Boot gets stuck at boot from MMC

Postby summers » Tue Aug 31, 2021 11:51 am

Oh yes - should have said. If your uboot saves its environment variables to flash/mmc (most distro uboot don't bother) - then you can set the boot delay in the environment variables ...
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Re: U-Boot gets stuck at boot from MMC

Postby Rethfor » Tue Aug 31, 2021 5:14 pm

$this->bbcode_second_pass_quote('summers', 'I')n your uboot defconfig file set the CONFIG_BOOTDELAY variable, e.g. in a file like: https://source.denx.de/u-boot/u-boot/-/tree/master/configs/pico-imx7d_defconfig set $this->bbcode_second_pass_code('', 'CONFIG_BOOTDELAY=5'). Then recompile and reflash. That will give a 5 second delay when you can interrupt uboot - and so type commands and see what is wrong. Also not that that file sets the BOOTCOMMAND so you can see what is run at boot time ...

Tried your suggestion but nothing changed, still I can't interrupt the process no matter how hard I try. I don't understand what can be the problem, could it be related to a hardware problem or something. Is custom carrier have any role in this process?
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Re: U-Boot gets stuck at boot from MMC

Postby summers » Tue Aug 31, 2021 7:43 pm

Odd. Did it count down before trying to boot? If not guess you either changed the wrong defconfig, or you defconfig is including another file that overwrites the change. So worth digging a bit. Part of the problem is your uboot isn't mainlined, so who can say what they have done. Maybe best going back to varicite, as it looks like their version of uboot ...
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