Re: [PATCH V3 8/8] ARM: dts: sunxi: add support for Anbernic RG-Nano

On Wed, 23 Aug 2023 16:25:54 -0500
Chris Morgan [off-list ref] wrote:

Hi,

From: Chris Morgan <redacted>

The Anbernic RG-Nano is a small portable game device based on the
Allwinner V3s SoC. It has GPIO buttons on the face and side for
input, a single mono speaker, a 240x240 SPI controlled display, a USB-C
OTG port, an SD card slot for booting, and 64MB of RAM included in the
SoC.

Working/Tested:
- SDMMC
- UART (for debugging)
- Buttons
- Charging/battery/PMIC
- Speaker
- USB Host and Gadget
- Display (at 60hz)

So this works now purely in software, by the panel driver constantly
scanning out a framebuffer region via SPI?
I wonder if enabling DMA support for SPI then helps the CPU load?
Though this might be a performance optimisation in a later patch set
(as it requires adding support for the V3s DMA controller).

Can you please specify the pin number (PF6) as a comment here, as done
in the other DTs? Because reading this "5 6" is not very intuitive.
Same for the other &pio GPIO references.

+	status = "okay";
+};
+
+&ehci {
+	status = "okay";
+};
+
+&i2c0 {
+	status = "okay";
+
+	gpio_expander: gpio@20 {
+		compatible = "nxp,pcal6416";
+		reg = <0x20>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		#interrupt-cells = <2>;
+		interrupt-controller;
+		interrupt-parent = <&pio>;
+		interrupts = <1 3 IRQ_TYPE_EDGE_BOTH>;
+		vcc-supply = <&reg_vcc3v3>;
+	};
+
+	axp209: pmic@34 {
+		reg = <0x34>;
+		interrupt-parent = <&pio>;
+		interrupts = <1 5 IRQ_TYPE_EDGE_FALLING>;
+	};
+
+	pcf8563: rtc@51 {
+		compatible = "nxp,pcf8563";
+		reg = <0x51>;
+	};
+};
+
+#include "axp209.dtsi"
+
+/* Out of alphabetical order for dependencies sake. */

I think you don't need this comment here.

+&battery_power_supply {
+	status = "okay";
+};
+
+&mmc0 {
+	broken-cd;
+	bus-width = <4>;
+	disable-wp;
+	vmmc-supply = <&reg_vcc3v3>;
+	vqmmc-supply = <&reg_vcc3v3>;
+	status = "okay";
+};
+
+&ohci {
+	status = "okay";
+};
+
+&pio {
+	vcc-pb-supply = <&reg_vcc3v3>;
+	vcc-pc-supply = <&reg_vcc3v3>;
+	vcc-pf-supply = <&reg_vcc3v3>;
+	vcc-pg-supply = <&reg_vcc3v3>;
+
+	spi0_3wire_pins: spi0-3wire-pins {
+		pins = "PC1", "PC2", "PC3";

Huh, interesting, is that because the display chip is purely
unidirectional? In any case, can you add a comment saying what's going
on, I guess: "MISO is not connected"?
And I wonder if "3 wire mode" is somewhat misleading here, since this
seems to refer to bidirectional SPI over a combined MISO/MOSI line, and
requires explicit controller support? Which the Allwinner controllers
lack?
I think for the node and alias name that's fine, but a comment would
clear things up.

The rest looks fine, though we would still need to fix the USB PHY
issue.

Cheers,
Andre

+		function = "spi0";
+	};
+};
+
+&pwm {
+	pinctrl-0 = <&pwm0_pin>;
+	pinctrl-names = "default";
+	status = "okay";
+};
+
+/* DCDC2 wired into vdd-cpu, vdd-sys, and vdd-ephy. */
+&reg_dcdc2 {
+	regulator-always-on;
+	regulator-max-microvolt = <1250000>;
+	regulator-min-microvolt = <1250000>;
+	regulator-name = "vdd-cpu";
+};
+
+/* DCDC3 wired into every 3.3v input that isn't the RTC. */
+&reg_dcdc3 {
+	regulator-always-on;
+	regulator-max-microvolt = <3300000>;
+	regulator-min-microvolt = <3300000>;
+	regulator-name = "vcc-io";
+};
+
+/*
+ * LDO1 wired into RTC, voltage is hard-wired at 3.3v and cannot be
+ * software modified. Note that setting voltage here to 3.3v for accuracy
+ * sake causes an issue with the driver that causes it to fail to probe
+ * because of a voltage constraint in the driver.
+ */
+&reg_ldo1 {
+	regulator-always-on;
+	regulator-name = "vcc-rtc";
+};
+
+/* LDO2 wired into VCC-PLL and audio codec. */
+&reg_ldo2 {
+	regulator-always-on;
+	regulator-max-microvolt = <3000000>;
+	regulator-min-microvolt = <3000000>;
+	regulator-name = "vcc-pll";
+};
+
+/* LDO3, LDO4, and LDO5 unused. */
+&reg_ldo3 {
+	status = "disabled";
+};
+
+&reg_ldo4 {
+	status = "disabled";
+};
+
+&spi0 {
+	pinctrl-0 = <&spi0_3wire_pins>;
+	pinctrl-names = "default";
+	status = "okay";
+
+	display@0 {
+		compatible = "saef,sftc154b", "panel-mipi-dbi-spi";
+		reg = <0>;
+		backlight = <&backlight>;
+		dc-gpios = <&pio 2 0 GPIO_ACTIVE_HIGH>;
+		reset-gpios = <&pio 1 2 GPIO_ACTIVE_HIGH>;
+		spi-max-frequency = <100000000>;
+
+		height-mm = <39>;
+		width-mm = <39>;
+
+		/* Set hb-porch to compensate for non-visible area */
+		panel-timing {
+			hactive = <240>;
+			vactive = <240>;
+			hback-porch = <80>;
+			vback-porch = <0>;
+			clock-frequency = <0>;
+			hfront-porch = <0>;
+			hsync-len = <0>;
+			vfront-porch = <0>;
+			vsync-len = <0>;
+		};
+	};
+};
+
+&uart0 {
+	pinctrl-0 = <&uart0_pb_pins>;
+	pinctrl-names = "default";
+	status = "okay";
+};
+
+&usb_otg {
+	dr_mode = "otg";
+	status = "okay";
+};
+
+&usb_power_supply {
+	status = "okay";
+};
+
+&usbphy {
+	usb0_id_det-gpios = <&pio 6 5 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
+	status = "okay";
+};