[iMX8QM MEK CAR] How to add a custom resolution dislay

[Jose1985]

Dear Team,

I am trying to connect a display of custom resolution 3840x1100 to the LVDS1 -> HDMI port. However, the EDID information shows only up to 1920x1080. When I connect the same display to Ubuntu Desktop I can see both 3840x1100 & 3840x2160 resolution and the display looks perfect.

In case, I connect the same to iMX8QM MEK, ultra HD resolutions are not listed in EDID.

Could you let me know how to add a custom resolution, specifically 3840x1100 so that I can see a perfect UI rendering?

Best regards

Jose1985

[nevozade]

Hello @Jose1985 , @Zhiming_Liu

I am facing a very similar problem with this issue. I want to display 2 LVDS + 1 HDMI screens but I still cannot get it. What was the result on this, does ldb1 work?

Best regards.

[Zhiming_Liu]

Only HDMI can support such display resolution, LVDS-HDMI bridge can't support such resolution.

[Jose1985]

Dear @Zhiming_Liu ,

I understand. We are using imx-automotive-11.0.0_1.1.0 on i.MX8QM MEK using the product mek_8q_car as product. I believe we have 2 LVDS-HDMI port and 1 HDMI TX port. We are okay to use the HDMI TX port if it is possible. So in this case, I have the following question

HW Platform: i.MX8QM MEK

SW Platform: imx-automotive-11.0.0_1.1.0 (Android 11)

Product: imx8q_mek_car

Our requirement:

a. Driver primary display via LVDS-HDMI-0 @ 1080p (This is working, no change required)

b. Disable secondary display running via LVDS-HDMI-1 @ 1080p ==> HDMI Tx(J6) @3840x1100@60 (Need to add this change)

1. Can Android detect HDMI TX (J6) port as a display port by default?

2. Should we flash dtbo file with multi-display support?

3. If HDMI Tx port is not enabled by default, could you let us know how to do so and this able to drive a display of custom resolution of 3840x1100.

Awaiting your reply soon on this urgent requirement.

Let me also attach the HDMI timings as received from display vendor.

Best regards

Libin Jose.

[Zhiming_Liu]

Hi @Jose1985 

For b,  you need disable ldb2  and ldb2_phy nodes in imx8qm-mek.dts

1.BSP suppot dp1.3 by default, you need use hdmi-dp board in below case.

https://community.nxp.com/t5/i-MX-Processors/i-MX8-Display-Port-Interface/m-p/809824#M124876

2.yes, you need flash dtbo-imx8qm-md

3.Timing write is set by hdmi firmware.I need confirm this with internal team.

[Jose1985]

Dear @Zhiming_Liu ,

For point b, I understood about disabling ldb2. However, at the same time, I need to enable HDMI Tx port (J6) to drive a custom display panel of 3840*1100@60. If you would require the data sheet from the LCD vendor, I can share.

Current working setup:

LVDS-HDMI-0 @1080p ==> Primary display

LVDS-HDMI-1 @1080p ==> Secondary display

Requirement change:

LVDS-HDMI-0 @1080p ==> Primary display

HDMI Tx (J6) @3840x1100@60 ==> Secondary display ==> Not working yet

Kindly note that we need to still drive 2 displays,  the primary display through LVDS-HDMI-0 @ 1080p and secondary display through HDMI Tx(J6) 3840x1100 @60.

In my understanding, we need to do below steps.

1. Enable HDMI port with display-timings in DTS file (In which file, an how?)

2. Define custom resoution in drm_edid.c (Can I use CVT command to get those info, for e.g. $ cvt 3840 1100 60)

3. Pass HDMI-A-2:3840x1100@60 or similar argument as kernel argument.

Please help at the earliest.

Best regards,

Jose1985