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linux-next/drivers/pci/pcie
Rafael J. Wysocki 379021d5c0 PCI / PM: Extend PME polling to all PCI devices
The land of PCI power management is a land of sorrow and ugliness,
especially in the area of signaling events by devices.  There are
devices that set their PME Status bits, but don't really bother
to send a PME message or assert PME#.  There are hardware vendors
who don't connect PME# lines to the system core logic (they know
who they are).  There are PCI Express Root Ports that don't bother
to trigger interrupts when they receive PME messages from the devices
below.  There are ACPI BIOSes that forget to provide _PRW methods for
devices capable of signaling wakeup.  Finally, there are BIOSes that
do provide _PRW methods for such devices, but then don't bother to
call Notify() for those devices from the corresponding _Lxx/_Exx
GPE-handling methods.  In all of these cases the kernel doesn't have
a chance to receive a proper notification that it should wake up a
device, so devices stay in low-power states forever.  Worse yet, in
some cases they continuously send PME Messages that are silently
ignored, because the kernel simply doesn't know that it should clear
the device's PME Status bit.

This problem was first observed for "parallel" (non-Express) PCI
devices on add-on cards and Matthew Garrett addressed it by adding
code that polls PME Status bits of such devices, if they are enabled
to signal PME, to the kernel.  Recently, however, it has turned out
that PCI Express devices are also affected by this issue and that it
is not limited to add-on devices, so it seems necessary to extend
the PME polling to all PCI devices, including PCI Express and planar
ones.  Still, it would be wasteful to poll the PME Status bits of
devices that are known to receive proper PME notifications, so make
the kernel (1) poll the PME Status bits of all PCI and PCIe devices
enabled to signal PME and (2) disable the PME Status polling for
devices for which correct PME notifications are received.

Tested-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
2011-10-14 09:05:31 -07:00
..
aer PCI: PCIe AER: add aer_recover_queue 2011-07-22 08:25:37 -07:00
aspm.c PCIe ASPM: forcedly -> forcibly 2011-06-29 14:24:14 +02:00
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_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
portdrv.h PCI/ACPI: Request _OSC control once for each root bridge (v3) 2011-01-14 08:55:41 -08:00