[RFC PATCH 3/3] serial: mxc: restore booting for imx8mn_bsh_smm_s2

[Fabio Estevam]

Hi Michael,

On Thu, May 15, 2025 at 5:12 PM Michael Nazzareno Trimarchi
<michael at amarulasolutions.com> wrote:

> The serial is not up at that time so we need to buffer the error and print later. Right now
> we are working on other fixes

Please share more details about the boot problem on the imx8mn_bsh_smm_s2 board.

Does a hang occur at SPL? Do you get anything in the console?

The mx8mn_bsh_smm_s2 board uses UART4 as the console.

The other i.MX8MN boards where we tested this patch used UART2.

UART4 does not have U-Boot/Linux permission by default.

TF-A enables the other UART port permission access at:
https://github.com/ARM-software/arm-trusted-firmware/blob/v2.12/plat/imx/imx8m/imx8mn/imx8mn_bl31_setup.c#L124-L143

Is the UART clock access falling in your case?

Is clk_enable_bulk() the one that fails?