IlI9431 white screen with F1C100S (lichee nano)

[mzashh]

so i am trying to get an ili9341 working with the lichee nano. some people have already done it so ik that it is possible but all im getting is a white screen, my display module has a CS pin and is working fine with the Adafruit ILI9341 library, fbtft loads fine but the display is still blank.

i used this guide https://lualiliu.github.io/website/f1c100s-fbtft.html

the kernel that i am using https://github.com/MiyooCFW/kernel

here are the dts and dtsi, i have the display set up under spi0, also kernel version is 4.14.0 suniv-f1c500s-miyoo-4bit-1.dts.txt suniv.dtsi.txt

also here is the dmesg with fbtft debug <7> dmesg-1.txt

[notro]

                reset-gpios = <&pio 4 11 GPIO_ACTIVE_LOW>;
                dc-gpios = <&pio 4 10 GPIO_ACTIVE_LOW>;

dc-gpios should be GPIO_ACTIVE_HIGH. The D/CX pin on the controller should be low when the command byte is sent and the driver does this by setting the gpio to zero. reset-gpios changed behaviour in some kernel version, but on 4.14 it should be GPIO_ACTIVE_HIGH.

[mzashh]

notro thanks for the reply, i did change it but it seems to be making no difference, the screen is still white

[notro]

A white display means that it's not been configured correctly. I assume you've verified that the init sequence in dmesg is the same as the adafruit library. You can try to lower the speed in case there's noise on the line. Apart from that it's gpio configuration or wiring issues that can break things.

[mzashh]

The init code is the same as UCGlib, and my display works fine with that library as well. The wiring is ok i have even tried soldering it directly. I tried lowering the speed still nothing. my only guess is that the gpio config might be messing something, up is there a particular command to like see what pins fbtft is using like other than the reset and DC ones or anything else i can try to verify?

[notro]

If your platform has a pinctrl driver, you can see the config under /sys/kernel/debug/pinctrl. The Raspberry Pi has a tool raspi-gpio that can dump the config directly from the registers, I don't know if something like that exists for your device.

[mzashh]

the pinctrl seems to be ok as well, i am using spi0 and using the correct pins

SUNXI_PIN(SUNXI_PINCTRL_PIN(C, 0),
      SUNXI_FUNCTION(0x1, "gpio_out"),
      SUNXI_FUNCTION(0x2, "spi0"),      /* CLK */
      SUNXI_FUNCTION(0x3, "mmc1")),     /* CLK */
SUNXI_PIN(SUNXI_PINCTRL_PIN(C, 1),
      SUNXI_FUNCTION(0x0, "gpio_in"),
      SUNXI_FUNCTION(0x1, "gpio_out"),
      SUNXI_FUNCTION(0x2, "spi0"),      /* CS */
      SUNXI_FUNCTION(0x3, "mmc1")),     /* CMD */
SUNXI_PIN(SUNXI_PINCTRL_PIN(C, 2),
      SUNXI_FUNCTION(0x0, "gpio_in"),
      SUNXI_FUNCTION(0x1, "gpio_out"),
      SUNXI_FUNCTION(0x2, "spi0"),      /* MISO */
      SUNXI_FUNCTION(0x3, "mmc1")),     /* D0 */
SUNXI_PIN(SUNXI_PINCTRL_PIN(C, 3),
      SUNXI_FUNCTION(0x0, "gpio_in"),
      SUNXI_FUNCTION(0x1, "gpio_out"),
      SUNXI_FUNCTION(0x2, "spi0"),      /* MOSI */
      SUNXI_FUNCTION(0x3, "uart0")),    /* TX */

so now i am really confused as to why its not working, is there some way i can debug it

i also tried a couple things, using UCGlib and an esp8266 the display works i also found out that the reset pin can be just kept high and doesn't need a gpio, also same for CS but it needs to be kept low, i tried this with my SOC and fbtft and im still getting a white screen, which kinda makes me to believe that there is no SPI signal coming out for some reason

[notro]

You can try a spi loopback test: https://elinux.org/RPi_SPI#Loopback_test

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