MIPI DSI on i.MX8MM not working on Scarthgap

[dpog]

After switching to the Scarthgap release from Kirkstone, the kenrnel does not bind the DSI devices to each other and the DSI-HDMI-Bridge LT8912b is not working any more. The kernel switched from 5.15 to 6.6. Did any changes occur, that could cause this? I did not change the device tree (Custom Board).

This messages keep repeating infinitly:

[ 16.051534] imx-drm display-subsystem: bound imx-lcdif-crtc.0 (ops lcdif_crtc_ops)
[ 16.059264] imx_sec_dsim_drv 32e10000.mipi_dsi: version number is 0x1060200
[ 16.066360] [drm:drm_bridge_attach] *ERROR* failed to attach bridge /soc@0/bus@32c00000/mipi_dsi@32e10000 to encoder DSI-34: -517
[ 16.078073] imx_sec_dsim_drv 32e10000.mipi_dsi: Failed to attach bridge: 32e10000.mipi_dsi
[ 16.086355] imx_sec_dsim_drv 32e10000.mipi_dsi: failed to bind sec dsim bridge: -517
[ 16.095315] lt8912 1-0048: failed to find dsi host

[dpog · Accepted solution]

The problem seems to result from a patch (d89078c37b10f05fa4f4791b71db2572db361b68) moving the lt8912_attach_dsi call from the lt8912_bridge_attach to probe function. Reverting this patch (introduced with Kernel 5.17) solves the problem. Thanks to @Zhiming_Liu for the hint in this post (https://community.nxp.com/t5/i-MX-Processors/IMX93-DSI-drm-drm-bridge-attach-ERROR-failed-to-attach-...)