10.1 Cap Touch Display Driver IC

[spfowler]

I have reviewed the datasheet for the Toradex 1212 10.1 display from Logic Technologies, LT170410-2WHC. the Datasheet doesn’t identify the Source driver with LVDS interface. I’m using this display in relationship to the Dahlia Carrier Board with the i.MX8MP SoM.

I’m currently comparing the DTSI file of this display to a new display using a FIT EK79202B driver IC. Currently the new display is experiencing a vertical syncing issue and I’m trying to identify root cause as it might be related to the display configuration.

Display Comparison

Column 1	Column 2	C	D	E	F	Column 3	H	Column 4	J
			Logic Technologies				NEW
			LT170410-2WHC				xxxxxx
			LVDS - 4 Channel				LVDS 4 Channel
Clock Frequency	1/Tc	68.9	71.1	73.4		68.2	72.4	78.5
Horizontal Display Area	tHD		1280				1280
HS period time	tH	1410	1440	1470		1380	1440	1500
HS Front Porch	tHFP					12	72	132
HS Back Porch	tHBP					88	88	88
HS Width	tHW					-	-	-
HS Width + BP + FP	tHW+tHBP+tHFP	60	160	190		100	160	220
Vertical display area	tVD		800				800
VS Period time	tV	815	823	833		824	838	872
VS Front Porch	tVFP					1	15	49
VS Back Porch	tVBP					23	23	23
VS Width	tVW					-	-	-
VS Width + BP + FP	tVW+tVBP+tVFP	15	23	33		24	38	72

DTSI File

Column 1	Column 2	Column 3	Column 4	E	F	G	H
	DTSI File				DTSI Update
	Original				New Display
68.9	71.1	73.4		68.2	72.4	78.5
	1280				1280
1341	1440	1469		1380	1440	1500
23	60	71		10	70	130
23	60	71		88	88	88
15	40	47		2	2	2
61	160	189		100	160	220
	800				800
816	823	832		824	838	872
5	7	10		9	13	47
5	7	10		13	23	23
6	9	12		2	2	2
16	23	32		24	38	72

Looking for input on the display comparison and how best approach for the display panel integration including modification of the DTSI file.

The External TI MIPI_LVDS bridge IC can generate a stable image at both display targets, the Logic Technologies and the new display.

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Hello! Thank you for sharing such detailed information. I understand you’re integrating a new LVDS panel (with FIT EK79202B driver IC) into your Verdin iMX8M Plus on the Dahlia Carrier Board and are having vertical sync issues, while your LT170410-2WHC panel is functioning correctly.

Let’s break down the best approach for stable LVDS integration and necessary DTSI (device tree) adjustments:

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1. Understand the Critical Device Tree Parameters

LVDS panel timing parameters in the device tree must precisely match those specified by your new panel’s datasheet. Key fields for a typical LVDS panel are:

• clock-frequency (in Hz)
• hactive, vactive (horizontal/vertical resolution)
• hsync-len, hfront-porch, hback-porch
• vsync-len, vfront-porch, vback-porch
• Color mapping/data mapping (fsl,data-mapping, data-mapping)

You’ll configure these within the display-timings node of your overlay.

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2. Map Datasheet Parameters to Device Tree Fields

Referencing your tables, you’ll want to extract timing fields for the NEW display:

LCD Timing	Device Tree Field	Value (typical or mid-range based on your table)
Pixel Clock Frequency	clock-frequency	72,400,000 (for 72.4 MHz for new display)
Horizontal active (pixels)	hactive	1280
Horizontal total (tH)	hactive + hfront + hback + hsync	1440
Vertical active (lines)	vactive	800
Vertical total (tV)	vactive + vfront + vback + vsync	838

For porch and sync calculation:

• hblank = total - active
• vblank = total - active
• Assign values to hsync-len, hfront-porch, and hback-porch based on proportions in datasheet or, if given, direct values.
• Assign values to vsync-len, vfront-porch, and vback-porch similarly.

Example Calculation (if values are given as in your table):

Suppose for hfront-porch = 70, hback-porch = 88, hsync-len = 2
Then: 70 (front) + 88 (back) + 2 (sync) = 160 (hblank)

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3. Device Tree Example Snippet

Here’s an example display-timings node for your NEW panel (please verify the porch/sync lengths as needed):

panel_lvds: panel-lvds {
    compatible = "panel-lvds";
    data-mapping = "jeida-24";           /* Or "vesa-24", depends on your panel */
    width-mm = <217>;
    height-mm = <136>;
    status = "okay";

    display-timings {
        native-mode = <&timing0>;
        timing0: timing0 {
            clock-frequency = <72400000>;        /* 72.4 MHz */
            hactive = <1280>;
            vactive = <800>;
            hfront-porch = <70>;
            hback-porch = <88>;
            hsync-len = <2>;
            vfront-porch = <13>;
            vback-porch = <23>;
            vsync-len = <2>;
            /* Optional: polarity flags */
            hsync-active = <0>;
            vsync-active = <0>;
            de-active = <1>;
            pixelclk-active = <0>;
        };
    };
};

If color is incorrect or image is unstable, try swapping jeida-24 for vesa-24 or adjusting with fsl,data-mapping properties as per this discussion:

LVDS1_B single mode

Dear all, i’m working with the following configuration: Apalis iMX8QM 4GB WB IT V1.1D Ixora Carrier Board V 1.2A DISTRO_VERSION = “6.8.2” DISTRO_CODENAME = “krikstone” 10.1 I am trying to connect LCD(RGB666) to Ixora carrier board. I want to connect LVDS1_B without using LVDS1_A (single mode) I am writing device tree overlay: &ldb2 { status = "okay"; …

More overlay examples:

Lvds display integration with imx8mp verdin and dahila carrier board

Hello, I am new to this toradex,working with the new imx8M plus SOM, LVDS panel display integration is on going to get prototype alive. Custom embedded Yocto Linux image is the way to go. Yocto reference project fetched from Index of /toradex-manifest.git -b scrathgap-7.x.y -m tdxref/default.xml tdx-reference-minimal-image created ok, and it boots nice, display is not yet connected. Verdin DSI to LVDS adapter will be used to connect custom display, tianma P0840XGF1MA00 panel at this time. Que…

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4. Color Mapping & Data Mapping

• If the image colors are swapped/tinted, try both "jeida-24" and "vesa-24" settings.
• Set both fsl,data-mapping and data-mapping properties in your overlay node for completeness.
• See LVDS color mapping notes here:
  Verdin iMX8M Plus | Toradex Developer Center

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5. Troubleshooting Tips

• Make sure your device tree overlay is being applied (check /proc/device-tree/).
• If timings seem correct but image is unstable, tweak the sync and porch settings by small increments, as LVDS panels can be sensitive to these margins.
• Confirm clock-frequency matches within the datasheet’s allowed range.
• If the TI MIPI-LVDS bridge works but direct mode does not, it’s likely timing or color mapping, not hardware.
• Ensure the LVDS interface is in 4-channel mode if your panel requires this.

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Summary of Integration Steps

1. Align the device tree timings (including sync and porch) to the new panel datasheet.
2. Set the appropriate color/data mapping (jeida-24, vesa-24, or as per your panel).
3. Test and fine-tune: Start with datasheet mid-values; adjust porch/sync if you see jitter, tearing, or sync loss.

Let me know if you want a ready-to-use overlay based on the exact datasheet specs, or if you have the direct register/timing details for the new panel!

Best regards,
Toradex AI Assistant.

[alex.tx]

@spfowler

Logic Technologies, LT170410-2WHC. the Datasheet doesn’t identify the Source driver

LVDS is a high-speed digital signaling standard, so you don’t need a dedicated driver for the display IC itself. Instead, you need an LVDS driver for the i.MX8M Plus SoC, and it should be configured to match the display’s parameters—such as resolution, pixel clock, sync timings, signal polarity, etc.

Please refer to this article for more details.

[spfowler]

Alex,

I am using the overlay.txt file is how I am changing the display configuration using the overlay method described within the link provided. The tables provided is the configuration difference between the Toradex evaluation display 1212 and the display that has been chosen for this integration platform. I modified the “display-lt170410_sn65dsi84_overlay.dtsi” file and had that recompiled for the evaluation platform. Also changing the overlay.txt file enabled the overlay and enabled the display VIA the Texas Instruments SN65DSI84 MIPI-LVDS bridge.

Reference I’m using the following evaluation image
Toradex Embedded Linux Reference Multimedia Image 7.3.0+build.8 (2025-7-03)

I put that file into the boot directory and changed the overlay.txt file to include the
verdin-imx8mp_dsi-to-lvds_panel-cap-touch-10inch-lvds_overlay.dtbo

Due to the bridge being able to generate a stable test image I believe that the source is the dataset being sent to the MIPI-LVDS bridge. We have tried the new .dtsi file in the above table but with no change to the failure mode.

Note: I tried uploading the .dtsi file and the a video of the evaluation platform with both displays active, but the system won’t allow me due to being a new user for reference on the issue.

[alex.tx]

Could you please share the datasheet for your display (not just the EK79202B IC) as well as your device tree overlay code?

[spfowler]

I can provide snippets of the display datasheet as necessary.

I’m not allowed to upload any files due to the following error.

“Sorry, new users can not upload attachments.” when I press the upload button.

Please advise how to attach files to the thread.

[alex.tx]

you can use our data server https://share.toradex.com/

[michael.tx]

Hi Scott,

Any updates for us here?

Best regards,

Michael Park
Toradex