imx8m(n): garbage on serial line

[Fabio Estevam]

Hi Heiko,

On Fri, Jun 10, 2022 at 7:29 AM Heiko Thiery <heiko.thiery at gmail.com> wrote:
>
> Hi,
>
> I just rebased my pending patch for adding support for the NXP imx8mn
> ddr3l evk board. When applying on the current master I see some
> garbage on the serial input.
>
> Can anyone confirm that behavior or is it just here?

Just tried booting on a imx8mn ddr4 evk and such a problem does not happen:

U-Boot SPL 2022.07-rc4-00007-g57bd363de7 (Jun 10 2022 - 09:42:49 -0300)
SEC0:  RNG instantiated
Normal Boot
WDT:   Started watchdog at 30280000 with servicing (60s timeout)
Trying to boot from BOOTROM
image offset 0x8000, pagesize 0x200, ivt offset 0x0
NOTICE:  BL31: v2.7(release):v2.7.0
NOTICE:  BL31: Built : 09:42:28, Jun 10 2022


U-Boot 2022.07-rc4-00007-g57bd363de7 (Jun 10 2022 - 09:42:49 -0300)

CPU:   Freescale i.MX8MNano Quad rev1.0 at 1200 MHz
Reset cause: POR
Model: NXP i.MX8MNano DDR4 EVK board
DRAM:  2 GiB
Core:  139 devices, 22 uclasses, devicetree: separate
WDT:   Started watchdog at 30280000 with servicing (60s timeout)
MMC:   FSL_SDHC: 1, FSL_SDHC: 2
Loading Environment from MMC... OK
In:    serial at 30890000
Out:   serial at 30890000
Err:   serial at 30890000
Net:   eth0: ethernet at 30be0000
Hit any key to stop autoboot:  0

Also tried booting on a imx8mm evk and did not see the serial garbage either.

Not sure why this happens on the imx8mn ddr3 evk and on the
kontron_sl_imx8mm though.

None of the boards I have physical access show the problem. The
Kontron board  have remote access only,
so not very easy to run git bisect.

Are you able to bisect it with the kontron_sl_imx8mm board?