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

[Drew Fustini <fustini@kernel.org>]

On Wed, Oct 07, 2026 at 10:03:34PM +0000, Yao Zi wrote:
> 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

Sorry about not following up on this sooner.

Han Gao - could you explain what the motivation was for 52MHz?

Thanks,
Drew