i.MX93 without a GPU, parallel RGB LCD

[davidpatton]

The i.MX93's we are getting have the 2D GPU removed so we have no graphics accelerator. Back with the i.MX6SX we just did basic frame buffer stuff, I assume the same here. But I cannot find much help. I'm just trying to get the penguin during boot.

We are using Yocto Scarthgap, so I believe the kernel is 6.6.36. I found a patch titled:

Add i.MX91/93 parallel display support

dated 12/01/2025, which makes it sound like the kernel I am currently using may not even support what I'm trying to do. Also, everything, at least in the source tree, is under gpu/drm, and again I have no gpu.

I built what I thought was a simple panel in the device tree, but the kernel freezes during boot:

&lcdif {

    status = "okay";

    display = <&display_conf>;

    display_conf: display-0 {

        bits-per-pixel = <16>; /* or 18, 16, etc. depending on your panel */

        bus-width = <18>;

        panel {

            compatible = "panel-simple";

            backlight = <&backlight>; /* phandle to your backlight node */

            status = "okay";

            display-timings {

                native-mode = <&timing0>;

                timing0: timing0 {

                    clock-frequency = <25000000>;

                    hactive = <800>;

                    vactive = <480>;

                    hback-porch = <8>;

                    hfront-porch = <8>;

                    vback-porch = <16>;

                    vfront-porch = <16>;

                    hsync-len = <4>;

                    vsync-len = <4>;

                    hsync-active = <0>;

                    vsync-active = <0>;

                    pixelclk-active = <0>;

                };

            };

        };

    };

};

Thanks!

[Manuel_Salas]

Hello @davidpatton 

I hope you are doing very well.

Please take a look to the imx91-11x11-evk-tianma-wvga-panel.dts.

There is an example of parallel display in i.MX91.

Best regards,

Salas.

[davidpatton]

Thanks, I'm good...will be much better once I see the display working.

I tried adding a display like in the example, but still nothing. I'm not at all certain I have my kernel configured correctly. Not having a GPU but seeing all of the code under "gpu" in the drivers directory is concerning me.

I'm adding my dts and kernel config....I also do not understand the "assigned-clock-rates" binding at all and what I should put there and what it's based on. I looked at the documentation, it didn't help...

Thanks!

[davidpatton · Accepted solution]

Even though I do not have chips with a GPU, I still used code under drivers/gpu, that was just a little confusing. Attached is the device tree that got it to work, for future reference.