i.MX ProcessorsのトピックIMX8MP LVDS does not work

IMX8MP LVDS does not work

koo_sensei — Thu, 11 May 2023 06:35:33 GMT

Hello.

I'm trying to work with mistubishi LVDS panel directly connected to LVDS of i.MX8m PLUS.
I'm working with custom board but it is based on imx8mp evk.

I refered to imx8mp-evk-jdi-wuxga-lvds-panel.dts, so this is the .dts what I made.

/ { lvds0_panel { compatible = "panel-lvds"; backlight = <&lvds_backlight>; status = "okay"; data-mapping = "jeida-24"; width-mm = <160>; height-mm = <120>; panel-timing { clock-frequency = <50000000>; hactive = <320>; vactive = <240>; hback-porch = <65>; hfront-porch = <65>; vback-porch = <14>; vfront-porch = <3>; hsync-len = <32>; vsync-len = <5>; hsync-active = <0>; vsync-active = <0>; de-active = <1>; pixelclk-active = <0>; power-on-delay = <40>; power-off-delay = <16>; relax-delay = <1000>; }; port { panel_lvds_in: endpoint { remote-endpoint = <&lvds_out>; }; }; }; }; &lcdif1 { status = "okay"; }; &lcdif2 { status = "okay"; }; &lcdif3 { status = "okay"; thres-low = <1 2>; /* (FIFO * 1 / 2) */ thres-high = 4>; /* (FIFO * 3 / 4) */ }; &ldb_phy { status = "okay"; }; &ldb { status = "okay"; fsl,dual-channel; lvds-channel@0 { fsl,data-mapping = "spwg"; status = "okay"; /delete-node/ port@1; port@1 { reg = <1>; lvds_out: endpoint { remote-endpoint = <&panel_lvds_in>; }; }; }; };

And according to dmesg log, panel-lvds probe completed. as I know, there should be the file something like /sys/class/drm/card1-LVDS-1, but there's file list of /sys/class/drm/ in my situation is pretty different.

root@imx8mpevk:/sys/class/drm# ls card0 renderD128 version

So, when I excute 'weston-flower' after weston-start, there's errors that says cannot find display.

root@imx8mpevk:~# weston-start root@imx8mpevk:~# weston-flower failed to connect to Wayland display: No such file or directory failed to create display: No such file or directory

I read many of NXP community articles that similar of my case, but any of them was not helpful.

Can I get any clue of this situation?

Re: IMX8MP LVDS does not work

Zhiming_Liu — Tue, 16 May 2023 02:29:53 GMT

The lvds driver isn't probed correctly.

For single channel panel, the dts node should like below.

&ldb { status = "okay"; lvds-channel@0 { fsl,data-mapping = "spwg"; fsl,data-width = <24>; status = "okay"; port@1 { reg = <1>; lvds_out: endpoint { remote-endpoint = <&xxxxx>; }; }; }; };

You should confirm the pixel format, jeida or spwg in panel-lvds

Re: IMX8MP LVDS does not work

koo_sensei — Wed, 17 May 2023 02:49:30 GMT

Dear @Zhiming_Liu .

I did you advised, but it does not work.

I'm using Kernel 5.4.70, and I checked some source code below /drivers/gpu.

Properties like 'fsl,data-mapping' and 'fsl,data-width' are used in "of_get_bus_format()" in /drivers/gpu/drm/bridge/fsl-imx-ldb.c. I add printk msg in "of_get_bus_format()" function but I cannot find my printk msg at dmesg log.

And of_get_bus_format() functions is called by function binds ldb, but Kernel does not call this function.
I also checked imx8mp_ldb_bind() in drivers/gpu/imx/imx8mp-ldb.c, and I don't know why imx8mp_ldb_bind() does not called.

Can you advise how can I bind LDB interface in 5.4.70 Kernel?

Re: IMX8MP LVDS does not work

SanthoshRajavel — Thu, 05 Feb 2026 11:54:19 GMT

@Zhiming_Liu Iam also facing the same problem in IMX8MPlus . Can you guide that