i.MX6UL: U-boot 2018.03 instability issue

[Sean Anderson]

On 6/18/21 6:17 AM, Rosario Borsellino wrote:
 > Hello everyone,
 >
 > This is the first time that I request help on a mailing list so tell me if I make anything wrong.
 >
 > I'm having hard time trying to debug an issue on U-boot 2018.03, built for a custom i.MX6UL platform.

Does this occur with 2021.04?

 >
 > During the porting from U-boot 2015.04, as I need to display a splashcreen, I enabled the CONFIG_VIDEO property (alongside with the required initializations on my board sources). This made the work (I can see the default DENX splash on video) but made the U-boot unstable.
 >
 > As an example, if I run any fdt command from the shell, U-boot hangs with a data abort. Here the printout:
 >
 > ...
 > => setenv loadfdt tftpboot ${fdtaddr} ${serverip}:${fdtfile}
 > => setenv fdtaddr 0x83000000
 > => setenv fdtfile rb/imx6ul-dave-devel.dtb
 > => setenv serverip 192.168.0.13
 > => setenv ipaddr 192.168.0.83
 > => run loadfdt
 > Using FEC0 device
 > TFTP from server 192.168.0.13; our IP address is 192.168.0.83
 > Filename 'rb/imx6ul-dave-devel.dtb'.
 > Load address: 0x88000000
 > Loading: ########
 >           1.2 MiB/s
 > done
 > Bytes transferred = 38141 (94fd hex)
 > => fdt addr ${fdtaddr}
 > => fdt print /cb
 > data abort
 > pc : [<8ff460c0>]          lr : [<8ff4c2c9>]
 > reloc pc : [<878000c0>]    lr : [<878062c9>]

What functions/lines are these? You can use objdump -S and grep for the
reloc pc and lr (or look at u-boot.map, but that will not give you line
numbers)

--Sean

 > sp : 8df45cf8  ip : 00000000     fp : 00000003
 > r10: 8df50cd8  r9 : 8df45eb0     r8 : 00000003
 > r7 : fffffff5  r6 : 00000020     r5 : 00000000  r4 : 8ffbf514
 > r3 : 00000001  r2 : 0000894c     r1 : 000000d8  r0 : fffffff5
 > Flags: nzcv  IRQs on  FIQs on  Mode SVC_32
 > Resetting CPU ...
 >
 > resetting ...
 >
 > U-Boot SPL 2018.03-munich-2.0.0-rc4 (Jun 18 2021 - 09:16:52 +0200)
 > ...
 >
 > But the instability is not only related to these commands (I use this as a PASS/FAIL test), so I don't either know where to check.
 >
 > Debugging via JTAG, with Trace32 tool, I can make the command print the requested node, but only if I run step-by-step.
 >
 > I found that CONFIG_VIDEO property enables by default the CONFIG_CONSOLE_MUX property, disabling the latter the fdt test pass.
 >
 > Has anyone ever seen this behaviour and can address me to find the root cause?
 >
 > I'm working on top of NXP stable branches, so I don't know if I can find help here. I also enbled the SPL build which is not officially supported by NXP. Let me know what printouts, code snippet or test to perform I need to share to help in the identification of the problem.
 >
 > Best regards,
 >