[amdgpu] Kernel crashes on Fiji-based cards since kernel 5.7.x

Brief summary of the problem:

Seems to me the amdgpu has regression since kernel 5.7.0 (ppc64le 64K page size) for Fiji-based card.

Hardware description:

• CPU: IBM POWER9 8-core Sforza
• GPU: AMD Radeon R9 Nano
• System Memory: 64GB RAM ECC DDR4
• Display(s): Generic 1080p projector
• Type of Diplay Connection: HDMI

System information:

• Distro name and Version: Fedora 32 and 33
• Kernel version: 5.7.x to 5.9.x, 5.11.x to 5.12.x (64K page size CONFIG_PPC_64K_PAGES=y)
• Custom kernel: N/A

How to reproduce the issue:

• Boot Kernel version: 5.7.x to 5.9.x, 5.11.x to 5.12.x (64K page size CONFIG_PPC_64K_PAGES=y)
• Reboot and the kernel crashes

Attached files:

• dmesg.txt
• dmesg2.txt
• modinfo.txt
• Xorg log (N/A)

NOTES

• The driver can be loaded successfully on kernel 5.7.x by disabling Display Core (amdgpu.dc=0)
• The driver works perfectly on 5.10.19 (64K page size)
• The driver works perfectly on 5.7.x to 5.12.x (4K page size)