Re: [PATCH v2 2/4] riscv: dts: thead: add Milk-V Meles

[Yao Zi <me@ziyao.cc>]

On Thu, Oct 01, 2026 at 03:44:11PM +0800, Han Gao wrote:
> Add the Milk-V Meles board with UART0, eMMC, SD, Ethernet and the PWM2
> fan. Describe the board pin assignments and the PHY on the GMAC0 MDIO
> bus. Give GPIO banks aliases and name the exposed 40-pin header lines.
> 
> The eMMC I/O supply is fixed at 1.8 V. Enable DDR52 at that voltage and
> retain the 52 MHz board limit. Describe 8 GiB as the default memory
> size; firmware updates it to match the detected RAM capacity.
> 
> Reviewed-by: Drew Fustini <fustini@kernel.org>
> Signed-off-by: Han Gao <gaohan@iscas.ac.cn>
> ---
>  arch/riscv/boot/dts/thead/Makefile               |   1 +
>  arch/riscv/boot/dts/thead/th1520-milkv-meles.dts | 227 +++++++++++++++++++++++
>  2 files changed, 228 insertions(+)
> 
> diff --git a/arch/riscv/boot/dts/thead/Makefile b/arch/riscv/boot/dts/thead/Makefile
> index b55a17127c2bc06cbfb06d5f7c92dc7296e98437..25f7fe068368c97df2490bedc3eae70276a2e442 100644
> --- a/arch/riscv/boot/dts/thead/Makefile
> +++ b/arch/riscv/boot/dts/thead/Makefile
> @@ -1,2 +1,3 @@
>  # SPDX-License-Identifier: GPL-2.0
>  dtb-$(CONFIG_ARCH_THEAD) += th1520-lichee-pi-4a.dtb th1520-beaglev-ahead.dtb
> +dtb-$(CONFIG_ARCH_THEAD) += th1520-milkv-meles.dtb
> diff --git a/arch/riscv/boot/dts/thead/th1520-milkv-meles.dts b/arch/riscv/boot/dts/thead/th1520-milkv-meles.dts
> new file mode 100644
> index 0000000000000000000000000000000000000000..3714047190789bfccd8ff6810342d7ff865e74e4
> --- /dev/null
> +++ b/arch/riscv/boot/dts/thead/th1520-milkv-meles.dts
> @@ -0,0 +1,227 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
> +/*
> + * Copyright (C) 2021-2022 Alibaba Group Holding Limited.
> + * Copyright (C) 2026 Han Gao <gaohan@iscas.ac.cn>
> + */

...

> +&emmc {
> +	bus-width = <8>;
> +	max-frequency = <52000000>;
> +	cap-mmc-highspeed;
> +	mmc-ddr-1_8v;
> +	non-removable;
> +	no-sdio;
> +	no-sd;
> +
> +	status = "okay";
> +};

Could you please explain the 52MHz limitation? This doesn't match what
I saw at RevyOS' downstream kernel, which seems the only distribution
supported by Milk-V officially.

Regards,
Yao Zi

[1]: https://github.com/revyos/th1520-linux-kernel/blob/a092d55649279e1c9bcda2769b8f6b4370fa2c94/arch/riscv/boot/dts/thead/th1520-milkv-meles.dts#L1012-L1023