3.5" MIPI-DSI Display support on PicoCore MX7ULP

  • Hi,


    I recently ordered 2 evaluation kits for your PicoCore MX7ULP and these came with a 3.5" LCD touchscreen (SKU: B.LCD.22).

    Before starting customization of the image and deploy self-compiled binaries, I wanted to try the default factory-installed image first. I could successfully start the image and get to a console over the serial line but nothing is displayed on the attached LCD screen, even if I can see that an X server is started and running with a matchbox window manager on top of it as shown in following output of ps command:


    Looking at the device tree from U-Boot I see that the lcd_panel in mipi_dsi device is configured for another LCD display "TIANMA_PANEL_TM050JDHG33" that is definitely not matching the specs of your reference B.LCD.22 screen shipped with evaluation kits.


    mipi_dsi@40A90000 {

    compatible = "fsl,imx7ulp-mipi-dsi";

    reg = <0x40a90000 0x00010000>;

    interrupts = <0x00000000 0x0000002e 0x00000004>;

    clocks = <0x00000002 0x00000047>;

    clock-names = "mipi_dsi_clk";

    data-lanes-num = <0x00000002>;

    phy-ref-clkfreq = <0x016e3600>;

    max-data-rate = <0x2faf0800>;

    sim = <0x00000010>;

    status = "okay";

    pinctrl-names = "default", "sleep";

    pinctrl-0 = <0x00000021>;

    pinctrl-1 = <0x00000021>;

    lcd_panel = "TIANMA_PANEL_TM050JDHG33";

    resets = <0x00000022>;

    };


    Further looking in the MIPI DSI driver of iMX7ULP (drivers/video/fbdev/mxc/mipi_dsi_northwest.c from Buildroot release fsimx7ulp-B2019.12) I see that other LCD panels are supported but none seem to match your 3.5" LCD.


    1. Could you please provide a compatible compiled DTB that would work with your factory image installed on evaluation kit ?

    2. Could you provide updated sources that would allow me to later compile my own kernel with support for your B.LCD.22 LCD screen including touch support ?


    If you have any detailed documentation on the integration of this screen on the system, I would be interested (cabling, configuration in Linux kernel, enabling/disabling backlight, ...).


    Thanks for your support,

    Romain Bornet