ST7796 SPI Display on RockPi 4c+

#1

Hi,

I am trying to set up a Klipper install on my RockPi. I am running Armbian Linux 6.12.13-current-rockchip64 and have managed to get spi accelerometers and w1 digital thermometers running. However, now I’m stuck trying to get the screen to work.

The display appears to be a Sitronix st7796 and I’ve found a tutorial for a Raspberry Pi:


which in turn is based on this:

Now, i couldn’t quite figure out how to compile the driver - I would just get lots of errors like these and my attempt to just set it to armv8 didn’t work:
c++: error: unrecognized argument in option ‘-mabi=aapcs-linux’
c++: note: valid arguments to ‘-mabi=’ are: ilp32 lp64
c++: error: unrecognized argument in option ‘-mtls-dialect=gnu2’
c++: note: valid arguments to ‘-mtls-dialect=’ are: desc trad
c++: error: unrecognized argument in option ‘-mabi=aapcs-linux’
c++: note: valid arguments to ‘-mabi=’ are: ilp32 lp64

Next i attempted to just write a overlay - since klipper screen just runs on a external monitor without any configuration, i figured i might as well try it. What I ended up with is this:

/dts-v1/;
/plugin/;
/ {
	metadata {
		title = "Enable st7796 LCD (C) on SPI1";
		compatible = "rockchip,rk3399";
		category = "misc";
		exclusive = "GPIO1_B0", "GPIO1_A7", "GPIO1_B1", "GPIO1_B2", "GPIO4_D2", "GPIO4_D4", "GPIO4_D5" ;
		description = "Enable st7796 LCD (C) on SPI1.";
	};
};



&spi1 {
	status = "okay";
	#address-cells = <1>;
	#size-cells = <0>;
	pinctrl-names = "default", "high_speed";
	pinctrl-0 = <&spi1_clk &spi1_cs0 &spi1_rx &spi1_tx>;
	st7796: st7796@0 {
		compatible = "sitronix,st7796";
		reg = <0>;
		spi-max-frequency = <80000000>;
		#txbuflen = <32768>;
		rotate = <0>;
		#bgr = <0>;
		fps = <30>;
		buswidth = <8>;
		#regwidth = <16>;
		debug = <1>;
		reset-gpios = <&gpio4 29 0>;
		dc-gpios = <&gpio4 28 1>;
	};
};

When I enable this overlay, i get with sudo dmesg | grep spi:

[ 6.671760] SPI driver fb_st7796 has no spi_device_id for ilitek,st7796

Which to me sounds like there is a dirver available, just that something isn’t configured quite right. I’m also wondering why it says ilitek in the error message and not sitronix.

#2

It wokrs now! with some modification the the overlay file from @mrkprdo, the display now displays stuff!

/dts-v1/;
/plugin/;

/ {
        	metadata {
		title = "Enable st7789 LCD (C) on SPI1";
		compatible = "rockchip,rk3399";
		category = "misc";
		exclusive = "GPIO1_B0", "GPIO1_A7", "GPIO1_B1", "GPIO1_B2", "GPIO4_D4", "GPIO4_D5" ;
		description = "Enable st7789v LCD (C) on SPI1.";
	};

        fragment@0 {
                target = <&spi1>;
                __overlay__ {
                        #address-cells = <1>;
                        #size-cells = <0>;
                        pinctrl-0 = <&spi1_clk &spi1_cs0 &spi1_rx &spi1_tx>;
                        pinctrl-names = "default";
                        st7789v@0 {
	                        compatible = "sitronix,st7789v";
         	               status = "okay";
                 		       reg = <0>;
	                        spi-max-frequency = <10000000>;
         	               width = <240>;
                 		       height = <320>;
	                        buswidth = <8>;
         	               fps = <60>;
                 		       rotate = <270>;
	                        debug = <1>; // 等级0～7 越高信息越多
	                        reset-gpios = <&gpio4 29 1>;
				dc-gpios = <&gpio4 28 0>;
                 		       //led-gpios = <0x2b 73 0>;        // pin 18
                        };
                };
        };
};