Re: [PATCH 2/2] imx8mn/8mp: Select ENV_IS_NOWHERE

[Marek Vasut <marex@denx.de>]

On 4/20/22 23:07, Fabio Estevam wrote:
> From: Fabio Estevam <festevam@denx.de>
> 
> Currently, on i.MX8MN/i.MX8MP (Bootrom version 2) it is not possible to
> load U-Boot via serial download mode, unless CONFIG_ENV_IS_NOWHERE is
> selected.
> 
> This was noticed before by Adam Ford and fixed on the imx8mn beacon
> board in commit 2c7ebf7778cf ("imx: imx8mn_beacon: Fix USB booting").
> 
> Such commit log states:
> 
> "The i.MX8M Nano can boot over USB using the boot ROM instead of
> adding extra code to SPL to support USB drivers, etc.  However,
> when booting from USB, the environment doesnt' know where to load
> and causes a hang.  Fix this hang by supporting CONFIG_ENV_IS_NOWHERE=y.
> It only falls back to this condition when booting from USB, so it
> does not impact MMC booting."

I suspect this happens because

arch/arm/mach-imx/imx8m/soc.c env_get_location()

contains
"
...
default:
  return ENVL_NOWHERE;
"

right ?

I wonder what would happen if you were to add:

case USB_BOOT:
   return ENVL_UNKNOWN;

Maybe that would even work without CONFIG_ENV_IS_NOWHERE=y ?