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| author | Lukas Wunner <lukas@wunner.de> | 2016-09-18 06:39:20 +0300 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2016-09-28 19:49:21 +0300 |
| commit | a0d2a959d3da343554523d26902de1d40a9e5c28 (patch) | |
| tree | 9fe0d30920a8e2a3107d67a451ab48d1bf394502 /drivers/pci/pci.h | |
| parent | a6a64026c0cd1a76a0c8ab1c05a421aa4821887b (diff) | |
| download | linux-a0d2a959d3da343554523d26902de1d40a9e5c28.tar.xz | |
PCI: Avoid unnecessary resume after direct-complete
Commit 58a1fbbb2ee8 ("PM / PCI / ACPI: Kick devices that might have been
reset by firmware") added a runtime resume for devices that were runtime
suspended when the system entered sleep.
The motivation was that devices might be in a reset-power-on state after
waking from system sleep, so their power state as perceived by Linux
(stored in pci_dev->current_state) would no longer reflect reality. By
resuming such devices, we allow them to return to a low-power state via
autosuspend and also bring their current_state in sync with reality.
However for devices that are *not* in a reset-power-on state, doing an
unconditional resume wastes energy. A more refined approach is called for
which issues a runtime resume only if the power state after direct-complete
is shallower than it was before. To achieve this, update the device's
current_state and compare it to its pre-sleep value.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/pci/pci.h')
0 files changed, 0 insertions, 0 deletions