[i.MX8MP][Android 11.0.0_2.2.0] LVDS Panel PWM Signal Fail

[TarkerHu]

[Software Version]:
Android 11.0.0_2.2.0
https://www.nxp.com/webapp/sps/download/license.jsp?colCode=11.0.0_2.2.0_ANDROID_SOURCE&appType=file...

Hi,
I was using i.MXP8M PLUS and was porting LVDS Panel.
I've modified nothing. Using NXP default codebase:
And download using cmd:
uuu_imx_android_flash.bat -f imx8mp -a -e -u trusty -d lvds-panel

I used LVDS0.But I found LVDS Panel Backlight control signal:
(1) Pin: LVDS_BL_PWM. It looks like 1.8V, but it should be 3.6v.
(2) PIN: LVDS_EN. It should be high 3.6V. But it’s always low.

[Questions]
Is this correct due to default codebase?
How can I make PWM workable? (Pin: LVDS_BL_PWM , and PIN: LVDS_EN)

Best,

Tarker

 

[Zhiming_Liu]

As  quick user guide has said,default code is for dual channel lvds panel:

To test the LVDS panel display, use two i.MX mini SAS cables to connect the LVDS panel to the "LVDS0" and "LVDS1" ports. Provide 5V power through the DC jack on the LVDS panel or connect pin3 with pin4 of pin header j7 beside the DC jack.

You can follow this dts to port your lvds0 panel.

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mp-evk-j...

[TarkerHu]

Hi nxf65025,

Thank you for replying.

The link

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mp-evk-j...

 You've gave me is the same as mine. We did not modify it.

But why LVDS_BL_PWM and LVDS_EN cannot work? 

Do these 2 backlight control pins have any dependency with LVDS0/LVDS1 signal?

[Zhiming_Liu]

But why LVDS_BL_PWM and LVDS_EN cannot work? 

---> The driver doesn't work.  you can try to use 'uuu xxxx lvds-panel'

[TarkerHu]

Hi nxf65025,

But why LVDS_BL_PWM and LVDS_EN cannot work? 

---> The driver doesn't work.  you can try to use 'uuu xxxx lvds-panel'

Could you explain more clearly? As my original questions, I was using 

"uuu_imx_android_flash.bat -f imx8mp -a -e -u trusty -d lvds-panel"

Is there anything needed to be modified?

Best,

Tarker

[Zhiming_Liu]

Did you set uboot bootargs about lvds?

[TarkerHu]

I tried as below ASAP. But Pins are still as before (LVDS_BL_PWM, LVDS_EN) = (1.8V, low) ?

==============

U-Boot > setenv bootargs console=ttymxc1,115200 earlycon=ec_imx6q,0x30890000,115200 init=/init androidboot.console=ttymxc1 androidboot.hardware=nxp cma=960M@0x400M-0x1000M androidboot.primary_display=imx-drm firmware_class.path=/vendor/firmware loop.max_part=7 androidboot.vendor.sysrq=1 transparent_hugepage=never androidboot.wificountrycode=CN moal.mod_para=wifi_mod_para.conf androidboot.lcd_density=240 swiotlb=65536
U-Boot > saveenv

U-Boot > setenv append_bootargs androidboot.selinux=permissive
U-Boot > saveenv