kernel-fxtec-pro1x/drivers/pci/pcie
Matthew Garrett 10f6dc7eed PCI: Rework ASPM disable code
Right now we forcibly clear ASPM state on all devices if the BIOS indicates
that the feature isn't supported. Based on the Microsoft presentation
"PCI Express In Depth for Windows Vista and Beyond", I'm starting to think
that this may be an error. The implication is that unless the platform
grants full control via _OSC, Windows will not touch any PCIe features -
including ASPM. In that case clearing ASPM state would be an error unless
the platform has granted us that control.

This patch reworks the ASPM disabling code such that the actual clearing
of state is triggered by a successful handoff of PCIe control to the OS.
The general ASPM code undergoes some changes in order to ensure that the
ability to clear the bits isn't overridden by ASPM having already been
disabled. Further, this theoretically now allows for situations where
only a subset of PCIe roots hand over control, leaving the others in the
BIOS state.

It's difficult to know for sure that this is the right thing to do -
there's zero public documentation on the interaction between all of these
components. But enough vendors enable ASPM on platforms and then set this
bit that it seems likely that they're expecting the OS to leave them alone.

Measured to save around 5W on an idle Thinkpad X220.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
2012-01-06 12:10:26 -08:00
..
aer PCI: PCIe AER: add aer_recover_queue 2011-07-22 08:25:37 -07:00
aspm.c PCI: Rework ASPM disable code 2012-01-06 12:10:26 -08:00
Kconfig kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
Makefile PCI: PCIe: Move PCIe PME code to the pcie directory 2010-08-24 13:47:48 -07:00
pme.c PCI / PM: Extend PME polling to all PCI devices 2011-10-14 09:05:31 -07:00
portdrv.h PCI/ACPI: Request _OSC control once for each root bridge (v3) 2011-01-14 08:55:41 -08:00
portdrv_acpi.c PCI/ACPI: Request _OSC control once for each root bridge (v3) 2011-01-14 08:55:41 -08:00
portdrv_bus.c PCI: portdrv: remove unnecessary struct pcie_port_data 2009-12-04 15:56:19 -08:00
portdrv_core.c PCI: Disable ASPM when _OSC control is not granted for PCIe services 2011-03-21 09:41:08 -07:00
portdrv_pci.c PCI/PCIe: Clear Root PME Status bits early during system resume 2010-12-23 12:54:03 -08:00