IMX8MP LVDS does not work

[koo_sensei]

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?

[SanthoshRajavel]

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

[Zhiming_Liu]

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

[koo_sensei]

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?