help: vga behind pci bridge, bridge not forwarding

[abbrous]

hello,

I want to ask a question, anybody can help me?

I have a armv8 compatible machine, and my only vga device is behind a bridge, I found this bridge can not route address: vgaarb: decodes=io+mem,owns = none (in dmesg log). And I don't have PCI_PROBE_ONLY in device tree. AND I noticed in file vgaarb.c there just have one BRIDGE FORWARDING check in a while loop. Before this check, bridge forwarding bit (write PCI_BRIDGE_CTL_VGA to BRIDGE_CONTROL register?)havn't set in bus enumetation routine.

My question is how and where to add some code to repair this problem? Kernel version: 4.9.9.

Thanks in advance.

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