iMX8MM HDMI crtc

[dpog]

I'm currently integrating a DSI-to-HDMI bridge into our custom iMX8MM board. The bridge driver loads correctly, but I get no output on the display and get this message on boot:

[ 15.371306] imx-drm 32c00000.bus:display-subsystem: [drm] Cannot find any crt c or sizes

I attached the corresponding dts-Nodes, does anybody have some suggestions what I might be missing? I'm using the linux-imx 5-15 kernel.

[Blake001]

Thank you so much for your information.

I'm working on imx8mm and trying to use the lt8912b driver for lt8912

My kernel version is 6.6.23

I copied your dts.txt settings to the imx8mm-evk.dts, and I have this error repeating below:

[ 4.321983] lt8912 1-0048: failed to find dsi host
[ 4.351954] lt8912 1-0048: failed to find dsi host
[ 4.381217] lt8912 1-0048: failed to find dsi host
[ 4.412626] lt8912 1-0048: failed to find dsi host
[ 4.442807] lt8912 1-0048: failed to find dsi host

Did you add your changes to the same imx8mm-evk.dts, or did you use different version?

[dpog · Accepted solution]

For anyone who should stuble upon this, it simply was a typo.
In the devicetree node for the HDMI-connector there was a "ddc_i2c_bus" given, but the driver wants a "ddc-i2c-bus". With that corrected, the driver gets the EDID and produces an output

[Bio_TICFSL]

Hello,

I don't know how you change the source code and what display you use, if you  just want to change the lane, maybe you can try the dts file, for imx8MM, maybe you can try to use“ i2cset -f -y 2 0x0b 0x44 0x02 0x00 sp”

however it has been reported before but is fixed in latest kernel version, so please download the L6.1 BSP

https://www.nxp.com/design/software/embedded-software/i-mx-software/embedded-linux-for-i-mx-applicat...

Regards

[dpog]

Took me some time to get the L6.1 uboot running, but I now placed the dts in the "newer" Kernel and am facing this kernel log, repeating infinitly:
[ 14.218073] imx-drm 32c00000.bus:display-subsystem: bound imx-lcdif-crtc.0 (ops lcdif_crtc_ops)
[ 14.226972] imx_sec_dsim_drv 32e10000.mipi_dsi: version number is 0x1060200
[ 14.234015] [drm:drm_bridge_attach] *ERROR* failed to attach bridge /soc@0/bus@32c00000/mipi_dsi@32e10000 to encoder DSI-34: -517
[ 14.245696] imx_sec_dsim_drv 32e10000.mipi_dsi: Failed to attach bridge: 32e10000.mipi_dsi
[ 14.253971] imx_sec_dsim_drv 32e10000.mipi_dsi: failed to bind sec dsim bridge: -517
[ 14.263853] lt8912 1-0048: failed to find dsi host

I can't say which message comes first, I'm starting to debug it right now

[dpog]

@Bio_TICFSL 

The looping errors do not appear always, and when they don't, I get the same error as before, even thou I'm using L6.1

imx-drm 32c00000.bus:display-subsystem: [drm] Cannot find any crtc or sizes

[dpog]

@Bio_TICFSL
do you have any suggestions how I may procede?

[dpog]

I didn't change the source code. I'm guessing that I'm missing a display-timing node somewhere, but I already tried adding one at every possible location and got no result. I also looked up the device tree used in the display-selection-guide.

I also checked the bridge registers where the sizes should be stored, it seems as if the DSI signal isn't sending them