17:32 <jkangas> Hey all, I'm trying to test out the upstream r5f remoteproc/rpmsg drivers on a j784s4 evm and ran into trouble using rpmsg_char_simple to ping the main domain cores

17:33 <jkangas> I think I've traced it to the rpmsg_chrdev and ti.ipc4.ping-pong endpoints not being present for this core. All other cores (mcu domain r5f + dsp) have this, and I'm able to ping them successfully

17:35 <jkangas> Any advice on how I could troubleshoot this? I don't see anything in the main domain cores' trace buffers in debugfs (mcu domain core's trace buffer does show some logging), so I'm not sure if the firmware is trying to report any errors

17:54 <jkangas> A bit more detail on the test environment: the successful dsp/mcu r5f tests were done with the upstream v6.14 driver backported to a downstream kernel based on CentOS Stream 9

17:55 <jkangas> Also tried a 100% upstream kernel, but the rpmsg_chrdev + ping-pong endpoints that were present on the downstream kernel no longer showed up even though the rpmsg_char driver was loaded. I do see rpmsg_{ctrl,ns} in /sys/bus/rpmsg though