Ok great, the testing done so far appears to be pinpointing this to an issue fixed with newer kernel drm code. It's possible a specific patch resulted in the fix. In that case, the next logical step is to do a git bisection search on the kernel code to locate the fix. The procedure is a little technical but is well documented at https://wiki.ubuntu.com/Kernel/KernelBisection. I'll reassign to the kernel meanwhile.
Btw, drm code can be a bit thorny, and even if the solution is narrowed to a specific git commit, extracting and backporting it might be pretty tricky. But the kernel team can follow up with advice on the issue; please contact them if you have additional questions.
Ok great, the testing done so far appears to be pinpointing this to an issue fixed with newer kernel drm code. It's possible a specific patch resulted in the fix. In that case, the next logical step is to do a git bisection search on the kernel code to locate the fix. The procedure is a little technical but is well documented at https:/ /wiki.ubuntu. com/Kernel/ KernelBisection. I'll reassign to the kernel meanwhile.
Btw, drm code can be a bit thorny, and even if the solution is narrowed to a specific git commit, extracting and backporting it might be pretty tricky. But the kernel team can follow up with advice on the issue; please contact them if you have additional questions.