Luckfox Forums

I know I'm asking for a lot of trouble here, but I'll ask anyway.

I see that, out-of-box, Luckfox Lyra has support for a few DSI displays -- a few more than Raspberry Pi has (wink). However, I'm trying to use something physically smaller than 2.8". I have a few ST7789s lying around, and I know for a fact they will work with the Linux "panel" driver over SPI.

What I am looking for in the way of information:

1. Which DTS do I modify, if any, to set the chip up so it looks for the display on SPI0.0? SEE BELOW

2. How do I properly remove the overlay that keeps removing my kernel driver config to include the panel driver, instead of modifying said overlay? SEE BELOW

3. Where do I configure the display parameters, knowing that Luckfox doesn't have a "config.txt" in the same way that Raspberry Pi does?IGNORE THIS

Thanks

**UPDATE**

While poking around, I managed to get the driver to register, but I'm still having trouble getting the signals to actually output from the module. This is what I have done so far:

• Modified rk3506-display.config (I'm not sure how to prevent this from overriding my kernel config):

  Code: Select all

  CONFIG_DRM_PANEL_MIPI_DBI=m
  

• Added to rk3506-luckfox-lyra.dtsi:

  Code: Select all

  &spi0 {
  	status = "okay";
  	pinctrl-names = "default";
  	pinctrl-0 = <&rm_io7_spi0_clk &rm_io6_spi0_mosi &rm_io5_spi0_miso &rm_io4_spi0_csn0>;
  
  	dbi_panel: panel@1 {
  		compatible = "panel", "panel-mipi-dbi-spi";
  		reg = <0>;
  		spi-max-frequency = <40000000>;
  		dc_gpios=<&gpio0 RK_PA3 0>;
  		reset_gpios=<&gpio0 RK_PA2 0>;
  		backlight=<&gpio1 RK_PD3 0>;
  		width-mm = <33>;
  		height-mm = <33>;
  		write-only;
  		panel-timing {
  			hactive = <240>;
  			vactive = <240>;
  			hback-porch = <0>;
  			vback-porch = <0>;
  
  			clock-frequency = <0>;
  			hfront-porch = <0>;
  			hsync-len = <0>;
  			vfront-porch = <0>;
  			vsync-len = <0>;
  		};
  	};
  
  };
  

• added the appropriate firmware for my ST7789 display, per https://github.com/notro/panel-mipi-dbi/wiki

Any pointers on how to get the SPI and GPIO up and running would be appreciated. The driver isn't throwing any errors in `dmesg` so I'm imagining I must have the pin configuration wrong somehow.

1. Modify the DTS file corresponding to your board form factor, enable spi0, and configure the relevant pins and driver. If you need to use the SPI display as a framebuffer, you may refer to this device tree configuration (using the FBTFT driver). As for the tinydrm driver you mentioned, I have not used it before, and I am unsure whether it will conflict with Rockchip's driver (which requires the display to be bound to a VOP).

   Code: Select all

   /**********spi0**********/
   &spi0 {
   	status = "okay";
   	pinctrl-0 = <&rm_io1_spi0_clk &rm_io4_spi0_mosi &rm_io3_spi0_csn0>;
   	#address-cells = <1>;
   	#size-cells = <0>;
   
   	fbtft@0{
   		status = "okay";
   		compatible = "sitronix,st7789v";
   		reg = <0>;
   		spi-max-frequency = <50000000>;
   		fps = <60>;
   		buswidth = <8>;
   		debug = <0x7>;
   		dc-gpios = <&gpio0 RK_PA2 GPIO_ACTIVE_HIGH>;      //DC
   		reset-gpios = <&gpio0 RK_PA0 GPIO_ACTIVE_LOW>;    //RES
   	};
   };

2. After running ./build.sh config, select Kernel and set the defconfig fragments to empty. This will prevent the kernel configuration from being overwritten.
3. config.txt is a mechanism specific to the Raspberry Pi. On the Luckfox Lyra, the initialization sequence and resolution must be properly configured directly in the driver source code.