Comment 99 for bug 760131

On page 3 of the Phoronix thread:

http://phoronix.com/forums/showthread.php?56437-Burning-Through-Power-Linux-Regressions-Found/page3

Michael says there is a fix as long as you don't have a bad BIOS. This statement makes me think it might be this patch that disables ASPM for some hardware:

PCI: Disable ASPM if BIOS asks us to
https://lkml.org/lkml/2010/12/2/303

I have a shell script to set a bunch of low power setting and it started printing an "Operation not permitted" error when it tried to:

echo powersave > /sys/module/pcie_aspm/parameters/policy

I didn't know the cause, but it was related to a kernel upgrade a while back.

Recently, I found this message in the boot messages:

kernel: pci 0000:08:00.0: disabling ASPM on pre-1.1 PCIe device. You can enable it with 'pcie_aspm=force'

I tried adding that flag to the boot parameters in my grub config and have had no problems for the last couple weeks. I cannot report any difference in battery life since I rarely run my laptop unplugged. There seems to be no difference in the number of wakeups reported by Powertop.

There was also an earlier patch to disable ASPM:

https://lkml.org/lkml/2011/3/4/246

If this is the cause of the increase in power use, then it is not really a bug or a regression. It is a deliberate change to fix a problem with certain hardware. It's easy enough for everyone to test out stability with the flag to force ASPM on.