[Buildroot] Trouble with u-boot on a ZynqMP board

[Luca Ceresoli]

Hi Alvaro,

On 22/06/21 07:58, Alvaro Gamez wrote:
> Hi, Luca
> 
> El mié, 16 jun 2021 a las 22:52, Luca Ceresoli
> (<luca at lucaceresoli.net>) escribió:
>>
>> Hi Alvaro,
>>
>> On 15/06/21 09:50, Alvaro Gamez wrote:
>>> Hi!
>>>
>>> I'm trying to use buildroot to generate a system for the Digilent
>>> Genesys board, which is based on the zynqmp SOC. Thanks to the
>>> wonderful job of Luca and others, it should be pretty straightforward,
>>> but I'm having trouble getting it to boot, and I was hoping I could
>>> get some guidance on what to do next.
>>
>> Thanks for your appreciation! However I must say setting up zynqmp
>> booting is never straightforward... :-/
> 
> Yeah, tell me about it :)
> 
>>
>>> I'm using buildroot version 2021.05, with u-boot version 2021.04,
>>> which has latest patches that should allow booting completely via
>>> u-boot, without using Xilinx' FSBL
>>>
>>> I'm using Digient's reference design to generate configuration object
>>> pm_cfg_obj.c and PSU init file psu_init_gpl.c, which shall be fed to
>>> u-boot. Alongside these files, I'm make buildroot download a generic
>>> PMU firmware built by Luca at
>>> https://github.com/lucaceresoli/zynqmp-pmufw-binaries/raw/master/bin/pmufw-v2018.3.bin
>>> and here is the relevant configuration:
>>>
>>> BR2_TARGET_UBOOT=y
>>> BR2_TARGET_UBOOT_USE_CUSTOM_CONFIG=y
>>> BR2_TARGET_UBOOT_CUSTOM_CONFIG_FILE="$(BR2_EXTERNAL_Genesys_PATH)/uboot_defconfig"
>>> BR2_TARGET_UBOOT_NEEDS_DTC=y
>>> BR2_TARGET_UBOOT_SPL=y
>>> BR2_TARGET_UBOOT_SPL_NAME="spl/boot.bin"
>>> BR2_TARGET_UBOOT_ZYNQMP=y
>>> BR2_TARGET_UBOOT_ZYNQMP_PMUFW="https://github.com/lucaceresoli/zynqmp-pmufw-binaries/raw/master/bin/pmufw-v2018.3.bin"
>>> BR2_TARGET_UBOOT_ZYNQMP_PM_CFG="/tmp/pm_cfg_obj.c"
>>> BR2_TARGET_UBOOT_ZYNQMP_PSU_INIT_FILE="/tmp/psu_init_gpl.c"
>>> BR2_TARGET_UBOOT_CUSTOM_DTS_PATH="$(BR2_EXTERNAL_Genesys_PATH)/orig.dts"
>>>
>>> To provide Arm Trusted Firmware, I'm passing buildroot the same
>>> configuration as already exists on configs/zynqmp_zcu106_defconfig
>>> which is:
>>>
>>> BR2_TARGET_ARM_TRUSTED_FIRMWARE=y
>>> BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_GIT=y
>>> BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_REPO_URL="https://github.com/ARM-software/arm-trusted-firmware.git"
>>> BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_REPO_VERSION="v1.5"
>>> BR2_TARGET_ARM_TRUSTED_FIRMWARE_PLATFORM="zynqmp"
>>> BR2_TARGET_ARM_TRUSTED_FIRMWARE_BL31_UBOOT=y
>>>
>>> The device tree I'm using is extracted from Digilent's kernel image,
>>> so it should be correct, although I had to manually patch u-boot to
>>> include my "orig.dtb" as a target of dtb-$(CONFIG_ARCH_ZYNQMP)
>>>
>>> So, it is assumption that this should make u-boot prompt appear after
>>> power up, but I must be wrong because nothing appears at all on the
>>> serial console.
>>>
>>> Provided image by Digilent follows the Xilinx' booting workflow, so
>>> only a BOOT.BIN file is on the sdcard which includes xilinx' FSBL, PMU
>>> firmware with configuration object, u-boot, kernel, device tree, etc,
>>> so at least I know that the board is fine as this firmware works
>>> flawlessly. I also was able to load the kernel and device tree as
>>> built by buildroot over this instance of u-boot, so at least I can
>>> load my own kernel, but I can't progress deeper than that.
>>
>> I can't point out a specific potential cause for your problem. I would
>> expect to see at least the U-Boot SPL prompt. You might want to enable
>> some debug outputs in the pmufw code to see it it starts at least.
> 
> I'm going all crazy about configuring U-Boot and my headache is noticeable now.
> Won't you happen to have a working u-boot with SPL defconfig that works on any
> particular zynqmp board?

No, sadly. I haven't been working on zynqmp for years.

> 
>> I haven't been working on zynqmp recently but back at the times
>> (2018~2019) one needed to have the various booting components "in sync",
>> expecially pmufw, U-Boot and SPL or FSBL. I don't remember whether ATF
>> was critical too in that respect. By "in sync" I mean the major version
>> number (the year) should be the same.
>>
>> Here you are using a 2018 pmufw and 2021 U-Boot so you muight want to
>> build a more recent pmufw and see if you get any improvements.
> 
> Great, that's a nice idea, thank you!

Try that, which seems to be required:
https://forums.xilinx.com/t5/Embedded-Linux/problem-on-u-boot-quot-Synchronous-Abort-quot-handler-esr/m-p/1060937/highlight/true#M39206

Also try with debug prints in the pmufw code.

-- 
Luca