Using uart1 on mediatek mt8195 derived board

[mbrugger]

El 2023-12-08 17:06, Thomas Schaefer va escriure:
> Hi Macpaul, Fabien,
> 
> I'm referring to patch series
> https://patchwork.ozlabs.org/project/uboot/patch/20230804110448.24589-1-macpaul.lin@mediatek.com/
> where support for the mediatek mt8195 SOC is introduced into u-boot.
> We are developing a board based on the mt8195 as well but we want to
> use UART1 instead of UART0 for debug output messages.
> 
> Our board is booting and we see boot messages on a debug pin header
> connected to UART0 when using the settings from the demo board, but
> when trying to switch to UART1, no more messages appear on the
> console. What we have tried is the following:
> 
> - Adaptation of the dts and dtsi files with uart1 settings taken from
> linux device tree:
> 
> diff --git a/arch/arm/dts/mt8195.dtsi b/arch/arm/dts/mt8195.dtsi
> index a7e4db5aa7..53eb437fad 100644
> --- a/arch/arm/dts/mt8195.dtsi
> +++ b/arch/arm/dts/mt8195.dtsi
> @@ -245,6 +245,17 @@
>                         status = "disabled";
>                 };
> 
> +               uart1: serial at 11001200 {
> +                       compatible = "mediatek,mt8195-uart",
> +                                    "mediatek,hsuart";
> +                       reg = <0 0x11001200 0 0x1000>;
> +                       interrupts = <GIC_SPI 91 IRQ_TYPE_LEVEL_LOW>;
> +                       clock-frequency = <26000000>;
> +                       clocks = <&clk26m>, <&clk26m>;
> +                       clock-names = "baud", "bus";
> +                       status = "disabled";
> +               };
> +
>                 pericfg_ao: syscon at 11003000 {
>                         compatible = "mediatek,mt8195-pericfg_ao", 
> "syscon";
>                         reg = <0 0x11003000 0 0x1000>;
> 
> diff --git a/arch/arm/dts/mt8195-kontron-sbc-i1200.dts
> b/arch/arm/dts/mt8195-kontron-sbc-i1200.dts
> index c6ea7e8f3d..4700a6d303 100644
> --- a/arch/arm/dts/mt8195-kontron-sbc-i1200.dts
> +++ b/arch/arm/dts/mt8195-kontron-sbc-i1200.dts
> @@ -58,7 +58,7 @@
>         };
> 
>         chosen {
> -               stdout-path = &uart0;
> +               stdout-path = &uart1;
>         };
> 
>         reg_1p8v: regulator-1p8v {
> @@ -121,7 +121,7 @@
>         status = "okay";
>  };
> 
> -&uart0 {
> +&uart1 {
>         status = "okay";
>  };
> 
> We also tried to change the DEBUG_UART settings in the defconfig to
> match with UART1, but without success.
> 
> Are there any special means to make UART1 interface run?

Did you had a look in the DTS from the kernel:
https://elixir.bootlin.com/linux/v6.7-rc6/source/arch/arm64/boot/dts/mediatek/mt8195.dtsi#L1040

My bet would be that infracfg_ao CLK_INFRA_AO_UART1 is not configured 
correctly.

Best regards,
Matthias.

> 
> Best regards,
> Thomas
> 
> Thomas Schäfer
> SW Design Engineer
> 
> T:
> +49 681 95916 203
> 
> 
> thomas.schaefer at kontron.com
> www.kontron.com
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