imx8m(n): garbage on serial line

[Heiko Thiery]

Hi Fabio,

Am Fr., 10. Juni 2022 um 16:13 Uhr schrieb Heiko Thiery
<heiko.thiery at gmail.com>:
>
> Hi,
>
> Am Fr., 10. Juni 2022 um 15:00 Uhr schrieb Fabio Estevam <festevam at gmail.com>:
> >
> > 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.
>
> Yes, this is strange.
>
> >
> > 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?
>
> Unfortunately only next week again. But I will try on my imx8mq later.

It took me some effort to get the current u-boot running on my imx8mq.
But finally it works and I do not see this garbage on the imx8mq. Next
week I will check on the kontron_sl_imx8mm.

> --
> Heiko