Re: [PATCH v4 2/2] riscv: dts: spacemit: add MusePi Pro board device tree

[Troy Mitchell <troy.mitchell@linux.spacemit.com>]

On Thu, Oct 23, 2025 at 04:53:53AM -0700, E Shattow wrote:
> On 10/23/25 00:28, Troy Mitchell wrote:
> > Add initial device tree support for the MusePi Pro board [1].
> > The board is using the SpacemiT K1/M1 SoC.
> > 
> > This device tree is adapted from the SpacemiT vendor tree [2] and
> > enables basic board functionality, including UART console, LED, eMMC,
> > Ethernet, and PDMA.
> > 
> > Link: https://developer.spacemit.com/documentation?token=YJtdwnvvViPVcmkoPDpcvwfVnrh&type=pdf [1]
> > Link: https://gitee.com/bianbu-linux/linux-6.6/blob/k1-bl-v2.2.y/arch/riscv/boot/dts/spacemit/k1-x_MUSE-Pi-Pro.dts [2]
> > Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
> > ---
> > Changelog in v4:
> > - modify commit message
> > - add SpacemiT copyright
> > - Link to v3: https://lore.kernel.org/all/20251017-k1-musepi-pro-dts-v3-2-40b05491699f@linux.spacemit.com/
> > 
> > Changelog in v3:
> > - sort dts node
> > - add ethernet alias
> > - add emmc, pdma, and eth0 node (a squash of patches 3–5 from v2)
> > - Link to v2: https://lore.kernel.org/all/20251010-k1-musepi-pro-dts-v2-2-6e1b491f6f3e@linux.spacemit.com/
> > 
> > Changelog in v2:
> > - modify commit message
> > - swap pinctrl-names and pinctrl-0 properties in uart0 node
> > - rename model: "MusePi Pro" -> "SpacemiT MusePi Pro"
> > - keep the dtb-$(CONFIG_ARCH_SPACEMIT) entries in alphabetical order
> > - Link to v1: https://lore.kernel.org/all/20250928-k1-musepi-pro-dts-v1-2-5efcca0ce3ae@linux.spacemit.com/
> > ---
> >  arch/riscv/boot/dts/spacemit/Makefile          |  1 +
> >  arch/riscv/boot/dts/spacemit/k1-musepi-pro.dts | 79 ++++++++++++++++++++++++++
> >  2 files changed, 80 insertions(+)
> > 
> > diff --git a/arch/riscv/boot/dts/spacemit/Makefile b/arch/riscv/boot/dts/spacemit/Makefile
> > index 152832644870624d8fd77684ef33addb42b0baf3..942ecb38bea034ef5fbf2cef74e682ee0b6ad8f4 100644
> > --- a/arch/riscv/boot/dts/spacemit/Makefile
> > +++ b/arch/riscv/boot/dts/spacemit/Makefile
> > @@ -1,4 +1,5 @@
> >  # SPDX-License-Identifier: GPL-2.0
> >  dtb-$(CONFIG_ARCH_SPACEMIT) += k1-bananapi-f3.dtb
> >  dtb-$(CONFIG_ARCH_SPACEMIT) += k1-milkv-jupiter.dtb
> > +dtb-$(CONFIG_ARCH_SPACEMIT) += k1-musepi-pro.dtb
> >  dtb-$(CONFIG_ARCH_SPACEMIT) += k1-orangepi-rv2.dtb
> > diff --git a/arch/riscv/boot/dts/spacemit/k1-musepi-pro.dts b/arch/riscv/boot/dts/spacemit/k1-musepi-pro.dts
> > new file mode 100644
> > index 0000000000000000000000000000000000000000..29e333b670cf0a5c4ed852668460db475b9c44cb
> > --- /dev/null
> > +++ b/arch/riscv/boot/dts/spacemit/k1-musepi-pro.dts
> > @@ -0,0 +1,79 @@
> > +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
> > +/*
> > + * Copyright (C) 2024 Yangyu Chen <cyy@cyyself.name>
> > + * Copyright (C) 2025 SpacemiT, Inc
> > + * Copyright (C) 2025 Troy Mitchell <troy.mitchell@linux.spacemit.com>
> > + */
> > +
> > +/dts-v1/;
> > +
> > +#include "k1.dtsi"
> > +#include "k1-pinctrl.dtsi"
> > +
> > +/ {
> > +	model = "SpacemiT MusePi Pro";
> > +	compatible = "spacemit,musepi-pro", "spacemit,k1";
> > +
> > +	aliases {
> > +		ethernet0 = &eth0;
> > +		serial0 = &uart0;
> > +	};
> > +
> > +	chosen {
> > +		stdout-path = "serial0";
> > +	};
> > +
> > +	leds {
> > +		compatible = "gpio-leds";
> > +
> > +		led1 {
> > +			label = "sys-led";
> > +			gpios = <&gpio K1_GPIO(96) GPIO_ACTIVE_HIGH>;
> > +			linux,default-trigger = "heartbeat";
> > +			default-state = "on";
> > +		};
> > +	};
> > +};
> > +
> > +&emmc {
> > +	bus-width = <8>;
> > +	mmc-hs400-1_8v;
> > +	mmc-hs400-enhanced-strobe;
> > +	non-removable;
> > +	no-sd;
> > +	no-sdio;
> 
> I doubt very much that 'no-sd' or 'no-sdio' are appropriate here. These
> are not general properties, they are useful only for specific
> workarounds of hardware that reacts badly to commands. Is the hardware
> broken that it needs these properties?
Thanks for the review. The three slots actually have distinct hardware
capabilities:
  - Slot 1 supports SD/SDIO (1/4 bit) and dual I/O voltage domains (1.8 V and 3.3 V).
  - Slot 2 supports SDIO/eMMC (1/4 bit) but does not support dual voltage domains.
  - Slot 3 supports only eMMC (1/4/8 bit) and is the only slot with a PHY.

Because of these differences, we need to explicitly specify no-sd and no-sdio
for slot 3 to prevent the MMC core from probing unsupported functions.

These are not general workarounds --—they reflect the actual hardware
limitations of the slots.