PCIe ASPM is an hardware power management protocol for PCI express devices. It allows a far better power management than what can be done with software power management at the price of an increased latency to the device. However some hardware don’t advertise it properly. And this was in fact the origin of the power regression case of 2.6.38 which was later fixed in 3.3.

It may also cause some Intel NIC (such as e1000e) to fall asleep unintentionally. So if you have an Intel NIC on Linux and it even fails to acquire an IPv4 address then you might try to add this option to your kernel command line : pcie_aspm=off. On Debian you can add this option to GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub and issue an update-grub.

You may also want to change the link-state of one specific device to L0/L1 at runtime. For this I’ll point you there : http://wireless.kernel.org/en/users/Documentation/ASPM.