drm error message at boot

[acremonini]

Hello,

I'm developing a Yocto distro for a custom board, starting from the one for imx8mp_evk. I'm trying to remove errors during the boot but there's three messages about ldb I can't explain. Notice that my lvds display works fine despite the messages.

[    0.183364] imx8mp-ldb ldb-display-controller: Failed to create device link (0x180) with 32e90000.lcd-controller
[    0.346205] imx8mp-ldb ldb-display-controller: Failed to create device link (0x180) with phy-lvds
[    0.375242] imx8mp-ldb ldb-display-controller: Failed to create device link (0x180) with lvds0_panel

After some debugging on on my board I've moved to the evk that has the same error.

[ 0.222956] imx8mp-ldb ldb-display-controller: Failed to create device link (0x180) with 32e90000.lcd-controller
[ 0.403848] imx8mp-ldb ldb-display-controller: Failed to create device link (0x180) with 1-004c
[ 0.467060] imx8mp-ldb ldb-display-controller: Failed to create device link (0x180) with 1-004c

I'm working on imx-linux-scarthgap distro with manifest imx-6.6.23-2.0.0.xml. Before this revision I worked with a mickledore one and no ldb error messages were printed on serial console.

Can someone help me removing this issue?

[SanthoshRajavel]

My Board 8MPLUSLPD4-EVK 

[SanthoshRajavel]

Hi @Manuel_Salas ,
Iam also facing the same issue in Scarthgap.

[ 0.090951] platform panel-lvds: Fixed dependency cycle(s) with /ldb-display- controller/lvds-channel@0
[ 1.605694] panel-lvds panel-lvds: /panel-lvds: problems parsing panel-timing (-22)
[ 1.613391] panel-lvds: probe of panel-lvds failed with error -22
[ 1.630510] imx8mp-ldb ldb-display-controller: Failed to create device link ( 0x180) with 32e90000.lcd-controller
[ 2.659304] imx8mp-ldb ldb-display-controller: Failed to create device link ( 0x180) with phy-lvds


My dts file 

// SPDX-License-Identifier: GPL-2.0+
/*
* i.MX8M Plus EVK
* LVDS Panel: 800x480 @ 60Hz
* Kernel: Linux 6.6+
*/

#include "imx8mp-evk.dts"

/ {
model = "NXP i.MX8M Plus EVK - LVDS 800x480";
compatible = "fsl,imx8mp-evk", "fsl,imx8mp";

panel_lvds: panel-lvds {
compatible = "panel-lvds";
status = "okay";

data-mapping = "vesa-24";
data-width = <24>;

display-timings {
native-mode = <&timing0>;

timing0: timing0 {
clock-frequency = <25005000>;

hactive = <800>;
hsync-len = <6>;
hback-porch = <14>;
hfront-porch = <44>;

vactive = <480>;
vsync-len = <1>;
vback-porch = <3>;
vfront-porch = <5>;
};
};

port {
panel_in: endpoint {
remote-endpoint = <&ldb_lvds_out>;
};
};
};
};

&ldb_phy {
status = "okay";
};

&ldb {
status = "okay";

port@0 {
reg = <0>;
ldb_lcdif_in: endpoint {
remote-endpoint = <&lcdif3_out>;
};
};

lvds-channel@0 {
status = "okay";
fsl,data-mapping = "vesa-24";
fsl,data-width = <24>;

port@1 {
reg = <1>;
ldb_lvds_out: endpoint {
remote-endpoint = <&panel_in>;
};
};
};
};

&lcdif3 {
status = "okay";

port {
lcdif3_out: endpoint {
remote-endpoint = <&ldb_lcdif_in>;
};
};
};

/* Disable HDMI controller ONLY */
&hdmi {
status = "disabled";
};

/* Disable MIPI + unused LCDIFs */
&mipi_dsi { status = "disabled"; };
&lcdif1 { status = "disabled"; };
&lcdif2 { status = "disabled"; };

can you help me to fix that . I also attach my display details . Could you address the issue

[Manuel_Salas]

Hello @acremonini 

I hope you are doing very well.

That error code 0x180 just means “no device found” at the time the link was attempted. It's more of a timing thing than an actual bug.

Since your LVDS display is working fine, it means the drivers eventually did their job. These logs are new in recent kernels (like 6.6 from Scarthgap). Older versions like Mickledore didn’t log this as an issue, which is probably why you hadn’t seen it before.

You can share your device tree and we can check if there is any inconsistency that is displaying this log.

Best regards,

Salas.