(In reply to higuita from comment #13)
> Can you give me any pointer how to "call the ACPI _PR3 method"?
> 
> i already install acpi_call, but have no idea how to use it

The pci core should be doing it for you since runtime pm support was added to
pcie ports:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9d26d3a8f1b0c442339a235f9508bdad8af91043
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=006d44e49a259b39947366728d65a873a19aadc0

Does adding:
pcie_port_pm=force
to the kernel command line in grub help?