PCI/PM: Fix config reg access for D3cold and bridge suspending
This patch fixes the following bug: http://marc.info/?l=linux-pci&m=134338059022620&w=2 Where lspci does not work properly if a device and the corresponding parent bridge (such as PCIe port) is suspended. This is because the device configuration space registers will be not accessible if the corresponding parent bridge is suspended or the device is put into D3cold state. To solve the issue, the bridge/PCIe port connected to the device is put into active state before read/write configuration space registers. If the device is in D3cold state, it will be put into active state too. To avoid resume/suspend PCIe port for each configuration register read/write, a small delay is added before the PCIe port to go suspended. Reported-by: NBjorn Mork <bjorn@mork.no> Signed-off-by: NHuang Ying <ying.huang@intel.com> Signed-off-by: NBjorn Helgaas <bhelgaas@google.com> Reviewed-by: NRafael J. Wysocki <rjw@sisk.pl>
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