[Buildroot] Nitrogen8M stuck at boot with master branch

[Emil Velikov]

On Wed, 16 Dec 2020 at 13:11, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>
> On Wed, 16 Dec 2020 at 13:10, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> >
> > Greetings everyone,
> >
> > Recently I've started thinkering with a Nitrogen8M SBC - the regular
> > one, not the Mini, Nano or SOM ones.
> >
> > Since this was my first experience with the board, initially I tried
> > the vendor provided Ubuntu image [1], which was working OOTB.
> >
> > Booting a minimal buildroot (make nitrogen8m_defconfig && make) seems
> > to be getting stuck as below. The full boot log attached.
> >
> Forgot the boot.log :-)
>
Upon a closer look, it appears that boot locks up during the first
arm_smccc_smc().
The one in busfreq_probe() for the vendor kernel or imx8m_ddrc_probe()
for the upstream ones.

Wild guess is that the built lpddr4_pmu_train firmware has regressed
or we're not using it properly.

As always, any hints will be appreciated.

Regards,
Emil