topic Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6 in i.MX Processors

panel-lvds driver does not work anymore after upgrade to kernel 6.6

MicMoba — Thu, 01 Aug 2024 11:17:04 GMT

Hi,

I upgrade my Linux kernel from 5.15.52 to 6.6. After upgrading my panel only shows a small stripe. I made no changes at the device tree. When I use the panel-simple driver instead of panel-lvds I got a working display. Does someone know about changes in the driver.

I use a iMX8MP and my panel is connected to LVDS1 interface.

dmesg shows a message but I can't identify the failure

dmesg | grep lvds [ 0.077630] platform panel-lvds1: Fixed dependency cycle(s) with /ldb-display-controller/lvds-channel@1 [ 2.511277] imx8mp-ldb ldb-display-controller: Failed to create device link (0x180) with phy-lvds [ 2.552129] imx8mp-ldb ldb-display-controller: Failed to create device link (0x180) with panel-lvds1

Thanks

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

Bio_TICFSL — Thu, 01 Aug 2024 14:43:18 GMT

Hello,

Have you checked the dtb? are they changed? which lvds device are you working on?

Regards

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

MicMoba — Thu, 01 Aug 2024 18:47:55 GMT

yes I checkd the dtb. I convert the dtb back to dts. The new one as the old one. I can't see any differences.

I use a DataModul 10,1“ TFT – WXGA – LVDS panel (TX26D207VM0AAA)

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

MicMoba — Thu, 01 Aug 2024 19:15:23 GMT

Here are my settings. Maybe you find a mistake

/ { backlight1: backlight1 { compatible = "pwm-backlight"; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_lvds1>; default-brightness-level = <6>; pwms = <&pwm3 0 50000 0>; power-supply = <&reg_lvds1_reg_en>; enable-gpios = <&gpio2 20 GPIO_ACTIVE_LOW>; brightness-levels= <0 4 8 16 32 64 128 255>; status = "okay"; }; panel_lvds: panel-lvds1 { compatible = "panel-lvds"; backlight = <&backlight1>; width-mm = <218>; height-mm = <137>; data-mapping = "vesa-24"; status = "okay"; panel-timing { clock-frequency = <71000000>; hactive = <1280>; hfront-porch = <30>; hsync-len = <48>; hback-porch = <80>; vactive = <800>; vfront-porch = <3>; vsync-len = <6>; vback-porch = <14>; }; port { panel1_in: endpoint { remote-endpoint = <&lvds1_out>; }; }; }; }; &lcdif2 { status = "okay"; }; /* LVDS1 */ &ldb { status = "okay"; lvds-channel@1 { #address-cells = <1>; #size-cells = <0>; status = "okay"; primary; port@1 { reg = <1>; lvds1_out: endpoint { remote-endpoint = <&panel1_in>; }; }; }; }; &ldb_phy { status = "okay"; };

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

tw22 — Mon, 30 Dec 2024 00:33:20 GMT

Failure occurs early during boot. This might indicate clocks problem. Check e. g. clock-names in node ldb read by drivers. What are you using? drm display-subsystem or frame buffers (mxc) ?

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

festevam — Fri, 07 Feb 2025 12:03:10 GMT

@MicMoba

This is an old thread, but I faced the same problem.

In my case, I had to pass the de-active = <1>; property to fix it.

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

brood — Tue, 05 Aug 2025 16:07:41 GMT

I have also been struggling with the same issue for over a week now, and adding this property ('de-active = <1>;') to the panel-timing definition in my device tree finally resolved the issue. My display works now, thanks for this! If I could give you more than 1 Kudo I would

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

SanthoshRajavel — Tue, 10 Feb 2026 14:20:11 GMT

Hi @brood

I am experiencing the same issue as well. Could you please share the DTS file in the chat? It would be very helpful.

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

brood — Tue, 10 Feb 2026 15:09:47 GMT

Hi @SanthoshRajavel,

Since my product is proprietary, I cannot share the contents of our DTS. However, this snippet from the above DTS shows where I added the 'de-active = <1>' property which was the fix I needed:

/ { backlight1: backlight1 { compatible = "pwm-backlight"; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_lvds1>; default-brightness-level = <6>; pwms = <&pwm3 0 50000 0>; power-supply = <&reg_lvds1_reg_en>; enable-gpios = <&gpio2 20 GPIO_ACTIVE_LOW>; brightness-levels= <0 4 8 16 32 64 128 255>; status = "okay"; }; panel_lvds: panel-lvds1 { compatible = "panel-lvds"; backlight = <&backlight1>; width-mm = <218>; height-mm = <137>; data-mapping = "vesa-24"; status = "okay"; panel-timing { clock-frequency = <71000000>; hactive = <1280>; hfront-porch = <30>; hsync-len = <48>; hback-porch = <80>; vactive = <800>; vfront-porch = <3>; vsync-len = <6>; vback-porch = <14>; de-active = <1>; }; port { panel1_in: endpoint { remote-endpoint = <&lvds1_out>; }; }; }; }; &lcdif2 { status = "okay"; }; /* LVDS1 */ &ldb { status = "okay"; lvds-channel@1 { #address-cells = <1>; #size-cells = <0>; status = "okay"; primary; port@1 { reg = <1>; lvds1_out: endpoint { remote-endpoint = <&panel1_in>; }; }; }; }; &ldb_phy { status = "okay"; };

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

SanthoshRajavel — Tue, 10 Feb 2026 15:18:39 GMT

@brood

@brood Thank you for sharing this. I already tried the same approach, but it did not work for me. I am also very new to this. Please find my code below—could you help me fix it?
My Board : 8MPLUSLPD4-EVK

#include "imx8mp-evk.dts"

/ {

backlight1: backlight1 {

compatible = "pwm-backlight";

pinctrl-names = "default";

pinctrl-0 = <&pinctrl_lvds1>;

default-brightness-level = <6>;

pwms = <&pwm3 0 50000 0>;

power-supply = <&reg_lvds1_reg_en>;

enable-gpios = <&gpio2 20 GPIO_ACTIVE_LOW>;

brightness-levels= <0 4 8 16 32 64 128 255>;

status = "okay";

};

panel_lvds: panel-lvds1 {

compatible = "panel-lvds";

backlight = <&backlight1>;

width-mm = <218>;

height-mm = <137>;

data-mapping = "vesa-24";

status = "okay";

panel-timing {

clock-frequency = <71000000>;

hactive = <1280>;

hfront-porch = <30>;

hsync-len = <48>;

hback-porch = <80>;

vactive = <800>;

vfront-porch = <3>;

vsync-len = <6>;

vback-porch = <14>;

de-active = <1>;

};

port {

panel1_in: endpoint {

remote-endpoint = <&lvds1_out>;

};

&lcdif2 {

status = "okay";

};

/* LVDS1 */

&ldb {

status = "okay";

lvds-channel@1 {

#address-cells = <1>;

#size-cells = <0>;

status = "okay";

primary;

port@1 {

reg = <1>;

lvds1_out: endpoint {

remote-endpoint = <&panel1_in>;

};

&ldb_phy {

status = "okay";

};

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

brood — Tue, 10 Feb 2026 15:42:35 GMT

@SanthoshRajavel I would check if the 'fsl,data-mapping' and 'fsl,data-width' properties in 'lvds-channel@1' node is correct. I have these defined in my own DTS to specific values expected by my panel, which differ from the defaults defined in the driver.

I would also verify the 'pinctrl-0' and 'pinctrl-names' property definitions - I see it in the backlight node definition which I think is not needed. This property is defined in my 'panel' node instead.

These are only pointers - I am by no means an expert in device tree configs but these things popped out as areas of interest.

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

SanthoshRajavel — Mon, 23 Feb 2026 14:43:21 GMT

@brood I have updated the backlight configuration, and the code builds successfully. The LVDS interface is now visible in DRM, but there is no output on the display. I am currently stuck at this stage. I have attached my code and the display details below for your review and suggestions.

// SPDX-License-Identifier: GPL-2.0+

#include "imx8mp-evk.dts"

{

panel_lvds: panel-lvds1 {

compatible = "panel-lvds";

backlight = <&lvds_backlight>;

width-mm = <165>;

height-mm = <104>;

data-mapping = "vesa-24";

status = "okay";

panel-timing {

clock-frequency = <29760000>; /* 29.76 MHz */

/* Horizontal */

hactive = <800>;

hfront-porch = <24>;

hsync-len = <72>;

hback-porch = <96>;

/* Vertical */

vactive = <480>;

vfront-porch = <3>;

vsync-len = <7>;

vback-porch = <10>;

/* Polarities */

hsync-active = <0>;

vsync-active = <0>;

de-active = <1>;

pixelclk-active = <0>;

};

port {

panel1_in: endpoint {

remote-endpoint = <&lvds1_out>;

};

&hdmi {

status = "okay";

};

&lcdif2 {

status = "okay";

};

/* LVDS1 */

&ldb {

status = "okay";

lvds-channel@1 {

#address-cells = <1>;

#size-cells = <0>;

status = "okay";

primary;

port@1 {

reg = <1>;

lvds1_out: endpoint {

remote-endpoint = <&panel1_in>;

};

&ldb_phy {

status = "okay";

};

Display : Innolux G070Y2-L01

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

tw22 — Mon, 23 Feb 2026 15:07:36 GMT

Maybe it helps. At your stage I remember this patch brought me further:

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -462,7 +462,7 @@ static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb)
* assume that another driver will enable the backlight at the
* appropriate time. Therefore, if it is disabled, keep it so.
*/
- return active ? FB_BLANK_UNBLANK: FB_BLANK_POWERDOWN;
+ return FB_BLANK_UNBLANK;
}

static int pwm_backlight_probe(struct platform_device *pdev)

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

brood — Mon, 23 Feb 2026 16:09:48 GMT

Are you using a HDMI panel? I see you have the HDMI node activated - that may be causing a conflict depending on your pinmux.

Re: panel-lvds driver does not work anymore after upgrade to kernel 6.6

SanthoshRajavel — Mon, 23 Feb 2026 16:51:25 GMT

@brood
Even after disabling HDMI and retrying the setup, the issue persists.

@MicMoba
I have a separate backlight module and I am controlling the backlight through that. In my case, an integrated backlight is not required.