On Friday, April 29, 2016 02:46:33 PM Mathias Nyman wrote: > On 29.04.2016 11:51, Mika Westerberg wrote: > > Current Linux PCI core does not do any kind of power management to PCIe > > ports. This means that we waste energy and consume laptop battery even if > > the port has nothing connected to. These patches aim to change that to the > > right direction. > > > > Previous versions of the patches can be found below: > > > > v1: http://www.spinics.net/lists/linux-pci/msg49313.html > > v2: http://www.spinics.net/lists/linux-pci/msg50167.html > > v3: http://www.spinics.net/lists/linux-pci/msg50345.html > > v4: http://www.spinics.net/lists/linux-pci/msg50665.html > > > > This assumes that recent (starting from 2015) PCIe ports are capable of > > transition to D3hot/D3cold. We add a new flag to struct pci_dev 'bridge_d3' > > that is set whenever the PCI core thinks the port can be put to D3. The > > check in pci_pm_suspend_noirq() is then extended to cover devices where > > 'bridge_d3' is set. > > > > We then add two new functions pci_bridge_d3_device_changed/removed(). These > > are used to set and clear 'bridge_d3' whenever there is a change in device > > power management policy (or if the device is removed). For example when > > userspace forbids the device to enter D3cold pci_bridge_d3_device_changed() > > will clear 'bridge_d3' of the upstream bridge. > > > > For all PCI ports where 'bridge_d3' is set we also enable and unblock > > runtime PM automatically. Only exception is when the PCIe port claims to > > support hotplug. More information about that is in the changelog of > > patch [4/4]. > > > > Since this also touches xhci, I'm adding Mathias and Greg to check if the > > change looks reasonable. > > > > For the non-functional one-line only xhci change in patch 2/4: > Acked-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> > > Out of curiosity, does enabling bridge d3 in any way impact #PME > wakeup signaling initiated by devices behind that bridge? If the device reports (via the config space) that it is capable of signaling PME from D3_{cold}, the wakeup signaling won't be affected (as long as the hardware design follows the spec). The Mika's patches take that into account AFAICS. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
