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Date:   Tue, 20 Sep 2022 10:31:36 +0200
From:   Alexander Dahl <ada@thorsis.com>
To:     Stefan Wahren <stefan.wahren@i2se.com>
Cc:     Ariel D'Alessandro <ariel.dalessandro@collabora.com>,
        bcm-kernel-feedback-list@broadcom.com, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-rpi-kernel@lists.infradead.org, arnd@arndb.de,
        f.fainelli@gmail.com, nsaenz@kernel.org, olof@lixom.net,
        robh+dt@kernel.org, soc@kernel.org, william.zhang@broadcom.com,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
Subject: Re: [PATCH] ARM: dts: Add Raspberry Pi Compute Module 4 CANOPi Board
Message-ID: <Yyl6aD7jXigk9UFX@ada.ifak-system.com>
Mail-Followup-To: Stefan Wahren <stefan.wahren@i2se.com>,
        Ariel D'Alessandro <ariel.dalessandro@collabora.com>,
        bcm-kernel-feedback-list@broadcom.com, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-rpi-kernel@lists.infradead.org, arnd@arndb.de,
        f.fainelli@gmail.com, nsaenz@kernel.org, olof@lixom.net,
        robh+dt@kernel.org, soc@kernel.org, william.zhang@broadcom.com,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
References: <20220916153156.30412-1-ariel.dalessandro@collabora.com>
 <YygeqySPtiAEN8EH@ada.ifak-system.com>
 <354a3ef2-c2df-e8fb-da15-b2271581959b@i2se.com>
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Hello Stefan,

Am Mon, Sep 19, 2022 at 01:18:21PM +0200 schrieb Stefan Wahren:
> Hi Alexander,
> 
> [fix address of Krzysztof]
> 
> Am 19.09.22 um 09:47 schrieb Alexander Dahl:
> > Hei hei,
> > 
> > Am Fri, Sep 16, 2022 at 12:31:56PM -0300 schrieb Ariel D'Alessandro:
> > > The Eclipse KUKSA CANOPi [0] is a baseboard for the Raspberry Compute
> > > Module 4 (CM4). It contains a VIA VL805 4 Port USB controller and two
> > > MCP251xFD based CAN-FD interfaces.
> > > 
> > > [0] https://github.com/boschresearch/kuksa.hardware
> > > 
> > > Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>
> > > ---
> > >   arch/arm/boot/dts/Makefile                    |   1 +
> > >   arch/arm/boot/dts/bcm2711-rpi-cm4-canopi.dts  | 139 ++++++++++++++++++
> > >   arch/arm64/boot/dts/broadcom/Makefile         |   1 +
> > >   .../dts/broadcom/bcm2711-rpi-cm4-canopi.dts   |   2 +
> > >   4 files changed, 143 insertions(+)
> > >   create mode 100644 arch/arm/boot/dts/bcm2711-rpi-cm4-canopi.dts
> > >   create mode 100644 arch/arm64/boot/dts/broadcom/bcm2711-rpi-cm4-canopi.dts
> > > 
> > > diff --git a/arch/arm/boot/dts/Makefile b/arch/arm/boot/dts/Makefile
> > > index 05d8aef6e5d2..8930ab2c132c 100644
> > > --- a/arch/arm/boot/dts/Makefile
> > > +++ b/arch/arm/boot/dts/Makefile
> > > @@ -98,6 +98,7 @@ dtb-$(CONFIG_ARCH_BCM2835) += \
> > >   	bcm2837-rpi-zero-2-w.dtb \
> > >   	bcm2711-rpi-400.dtb \
> > >   	bcm2711-rpi-4-b.dtb \
> > > +	bcm2711-rpi-cm4-canopi.dtb \
> > >   	bcm2711-rpi-cm4-io.dtb \
> > >   	bcm2835-rpi-zero.dtb \
> > >   	bcm2835-rpi-zero-w.dtb
> > > diff --git a/arch/arm/boot/dts/bcm2711-rpi-cm4-canopi.dts b/arch/arm/boot/dts/bcm2711-rpi-cm4-canopi.dts
> > > new file mode 100644
> > > index 000000000000..52ec5908883c
> > > --- /dev/null
> > > +++ b/arch/arm/boot/dts/bcm2711-rpi-cm4-canopi.dts
> > > @@ -0,0 +1,139 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/dts-v1/;
> > > +#include "bcm2711-rpi-cm4.dtsi"
> > > +
> > > +/ {
> > > +	model = "Raspberry Pi Compute Module 4 CANOPi Board";
> > > +
> > > +	clocks {
> > > +		clk_mcp251xfd_osc: mcp251xfd-osc {
> > > +			#clock-cells = <0>;
> > > +			compatible = "fixed-clock";
> > > +			clock-frequency = <20000000>;
> > > +		};
> > > +	};
> > > +
> > > +	leds {
> > > +		led-act {
> > > +			gpios = <&gpio 42 GPIO_ACTIVE_HIGH>;
> > > +		};
> > > +
> > > +		led-pwr {
> > > +			label = "PWR";
> > > +			gpios = <&expgpio 2 GPIO_ACTIVE_LOW>;
> > > +			default-state = "keep";
> > > +			linux,default-trigger = "default-on";
> > > +		};
> > > +	};
> > This looks like using the node name and the deprecated "label"
> > property for LED naming.  Please see
> > Documentation/devicetree/bindings/leds/common.yaml and use the
> > properties "function" and "color" instead.  Also check the node names
> > itself, see the example in that binding or the leds-gpio binding for
> > reference.
> 
> Oops, i didn't noticed this.
> 
> Unfortunately the ACT-LED is already a little bit opaque defined in
> bcm2835-rpi.dtsi:
> 
> leds {
> ?? ???? compatible = "gpio-leds";
> 
> ?? ???? led-act {
> ?? ???? ??? label = "ACT";
> ?? ???? ??? default-state = "keep";
> ?? ???? ??? linux,default-trigger = "heartbeat";
> ?? ???? };
> };
> 
> So a reference (currently missing) would have make it clear that the ACT-LED
> is common for all Raspberry Pi boards.

Yes, a reference would probably good, would make it easier to spot
this is already defined in the dtsi.

> So you wish that this is fixed for the CANOPi board or all Raspberry Pi
> boards?
> 
> I'm asking because switching to function would change the sysfs path and
> breaking userspace ABI.

You're right, and the effective label should stay as is for existing
boards to not break userspace.  

Not sure what the policy is for baseboards with compute modules.  Are
those LEDs on the compute module?  Or does the CM just expose those
GPIOs?  Is there some policy all baseboards must use them for LEDs?
An what about additional LEDs on the baseboard?  Is this allowed?  
(I don't think there a generic rules for that, but maybe some best
practices for certain SoMs like the RPi CM?)

IMHO for new independent boards though, new LEDs should not be
introduced the old way. I thought this is the case here, but it seems
I was wrong due to that baseboard vs. SoM thing.

Greets
Alex

> 
> > 
> > Greets
> > Alex
> > 
> > > +};
> > > +
> > > +&ddc0 {
> > > +	status = "okay";
> > > +};
> > > +
> > > +&ddc1 {
> > > +	status = "okay";
> > > +};
> > > +
> > > +&hdmi0 {
> > > +	status = "okay";
> > > +};
> > > +
> > > +&hdmi1 {
> > > +	status = "okay";
> > > +};
> > > +
> > > +&i2c0 {
> > > +	pinctrl-names = "default";
> > > +	pinctrl-0 = <&i2c0_gpio44>;
> > > +	status = "okay";
> > > +	clock-frequency = <100000>;
> > > +
> > > +	pcf85063a@51 {
> > > +		compatible = "nxp,pcf85063a";
> > > +		reg = <0x51>;
> > > +	};
> > > +};
> > > +
> > > +&pcie0 {
> > > +	pci@0,0 {
> > > +		device_type = "pci";
> > > +		#address-cells = <3>;
> > > +		#size-cells = <2>;
> > > +		ranges;
> > > +
> > > +		reg = <0 0 0 0 0>;
> > > +
> > > +		usb@0,0 {
> > > +			reg = <0 0 0 0 0>;
> > > +			resets = <&reset RASPBERRYPI_FIRMWARE_RESET_ID_USB>;
> > > +		};
> > > +	};
> > > +};
> > > +
> > > +&pixelvalve0 {
> > > +	status = "okay";
> > > +};
> > > +
> > > +&pixelvalve1 {
> > > +	status = "okay";
> > > +};
> > > +
> > > +&pixelvalve2 {
> > > +	status = "okay";
> > > +};
> > > +
> > > +&pixelvalve4 {
> > > +	status = "okay";
> > > +};
> > > +
> > > +&spi {
> > > +	status = "okay";
> > > +	pinctrl-names = "default";
> > > +	pinctrl-0 = <&spi0_gpio7>;
> > > +	cs-gpios = <&gpio 8 1>, <&gpio 7 1>;
> > > +	dmas = <&dma 6>, <&dma 7>;
> > > +	dma-names = "tx", "rx";
> > > +
> > > +	mcp251xfd0: mcp251xfd@0 {
> > > +		compatible = "microchip,mcp251xfd";
> > > +		reg = <0>;
> > > +		pinctrl-names = "default";
> > > +		pinctrl-0 = <&mcp251xfd0_pins>;
> > > +		spi-max-frequency = <20000000>;
> > > +		interrupt-parent = <&gpio>;
> > > +		interrupts = <27 IRQ_TYPE_LEVEL_LOW>;
> > > +		clocks = <&clk_mcp251xfd_osc>;
> > > +	};
> > > +
> > > +	mcp251xfd1: mcp251xfd@1 {
> > > +		compatible = "microchip,mcp251xfd";
> > > +		reg = <1>;
> > > +		pinctrl-names = "default";
> > > +		pinctrl-0 = <&mcp251xfd1_pins>;
> > > +		spi-max-frequency = <20000000>;
> > > +		interrupt-parent = <&gpio>;
> > > +		interrupts = <22 IRQ_TYPE_LEVEL_LOW>;
> > > +		clocks = <&clk_mcp251xfd_osc>;
> > > +	};
> > > +};
> > > +
> > > +&gpio {
> > > +	mcp251xfd0_pins: mcp251xfd0_pins {
> > > +		brcm,pins = <27>;
> > > +		brcm,function = <BCM2835_FSEL_GPIO_IN>;
> > > +	};
> > > +
> > > +	mcp251xfd1_pins: mcp251xfd1_pins {
> > > +		brcm,pins = <22>;
> > > +		brcm,function = <BCM2835_FSEL_GPIO_IN>;
> > > +	};
> > > +};
> > > +
> > > +&vc4 {
> > > +	status = "okay";
> > > +};
> > > +
> > > +&vec {
> > > +	status = "disabled";
> > > +};
> > > diff --git a/arch/arm64/boot/dts/broadcom/Makefile b/arch/arm64/boot/dts/broadcom/Makefile
> > > index e8584d3b698f..7cd88b8c0345 100644
> > > --- a/arch/arm64/boot/dts/broadcom/Makefile
> > > +++ b/arch/arm64/boot/dts/broadcom/Makefile
> > > @@ -1,6 +1,7 @@
> > >   # SPDX-License-Identifier: GPL-2.0
> > >   dtb-$(CONFIG_ARCH_BCM2835) += bcm2711-rpi-400.dtb \
> > >   			      bcm2711-rpi-4-b.dtb \
> > > +			      bcm2711-rpi-cm4-canopi.dtb \
> > >   			      bcm2711-rpi-cm4-io.dtb \
> > >   			      bcm2837-rpi-3-a-plus.dtb \
> > >   			      bcm2837-rpi-3-b.dtb \
> > > diff --git a/arch/arm64/boot/dts/broadcom/bcm2711-rpi-cm4-canopi.dts b/arch/arm64/boot/dts/broadcom/bcm2711-rpi-cm4-canopi.dts
> > > new file mode 100644
> > > index 000000000000..e9369aa0eb39
> > > --- /dev/null
> > > +++ b/arch/arm64/boot/dts/broadcom/bcm2711-rpi-cm4-canopi.dts
> > > @@ -0,0 +1,2 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +#include "arm/bcm2711-rpi-cm4-canopi.dts"
> > > -- 
> > > 2.37.2
> > >