imx8mqevk hdmi use

[richard_earle]

Hello:

I'm using an imx8mqevk and have successfully built a Linux Yocto image based on imx-linux-sumo with imx-4.14.78-1.0.0 with the Wayland backend. 

Using the HDMI to a pc monitor, everything boots as expected. I now wish to change the display to a 1280x800 TFT  display module. 

I have modified uboot's mmcargs to include the displayinfo variable as recommended in the i.mx Linux users's guide and confirmed the 1920x1080M@60 settings continue to work for the pc monitor.

It's unclear what the settings should be to support the 1280x800 TFT panel. If this is the correct approach, can you please supply the proper video settings for the displayinfo as they don't seem to exist in the i.MX Linux release notes.

I also just discovered the i.MX8MQ EVK Display Selection Guide, where if I'm interpreting things correctly, I will need to drive the 1280x800 over the MIPI-DSI HDMI display adapter. Could you please clarify / confirm - thanks

[richard_earle]

So it seems 1280x800 ~ standard resolution is only supported via the MIPI-DSI, which is fine, but it is still not clear what the boot args need to be to configure the MIPI-DSI to HDMI converter board.

[igorpadykov]

MIPI-DSI to HDMI board uses ADV7535 MIPI-DSI to HDMI converter:

fsl-imx8mq-evk-dcss-adv7535.dts\freescale\dts\boot\arm64\arch - linux-imx - i.MX Linux kernel 

linux/drivers/video/fbdev/mxc/adv7535.c

adv7535.c\mxc\fbdev\video\drivers - linux-imx - i.MX Linux kernel 

it uses fbdev drivers in .linux/drivers/video/fbdev/mxc

supported resolutions are in mxc_cea_mode[]

mxc_edid.c\mxc\fbdev\video\drivers - linux-imx - i.MX Linux kernel 

So one can try to debug it. May be helpful Linux L4.14.78_1.0.0 Documentation

Best regards
igor

[igorpadykov]

Hi Richard

supported resolutions are given in hdmi struct drm_display_mode edid_cea_modes[]

imx-hdp.c\hdp\imx\drm\gpu\drivers - linux-imx - i.MX Linux kernel 

hdmi driver in described in Linux Manual Linux L4.14.78_1.0.0 Documentation

seems such resolution is supported by boundary devices:

Boundary Devices 

Best regards
igor
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