From: Mika Westerberg Date: Fri, 13 Oct 2017 18:35:47 +0000 (+0300) Subject: PCI: pciehp: Do not clear Presence Detect Changed during initialization X-Git-Tag: v4.15-rc1~95^2~21^2 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=db63d40017a523d127ec78328fed643918c7c54c;p=linux.git PCI: pciehp: Do not clear Presence Detect Changed during initialization It is possible that the hotplug event has already happened before the driver is attached to a PCIe hotplug downstream port. If we just clear the status we never get the hotplug interrupt and thus the event will be missed. To make sure that does not happen, we leave Presence Detect Changed bit untouched during initialization. Then once the event is unmasked we get an interrupt and handle the hotplug event properly. Signed-off-by: Mika Westerberg Signed-off-by: Bjorn Helgaas --- diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c index fd0877e92b05..7bab0606f1a9 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -858,11 +858,16 @@ struct controller *pcie_init(struct pcie_device *dev) if (link_cap & PCI_EXP_LNKCAP_DLLLARC) ctrl->link_active_reporting = 1; - /* Clear all remaining event bits in Slot Status register */ + /* + * Clear all remaining event bits in Slot Status register except + * Presence Detect Changed. We want to make sure possible + * hotplug event is triggered when the interrupt is unmasked so + * that we don't lose that event. + */ pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, PCI_EXP_SLTSTA_ABP | PCI_EXP_SLTSTA_PFD | - PCI_EXP_SLTSTA_MRLSC | PCI_EXP_SLTSTA_PDC | - PCI_EXP_SLTSTA_CC | PCI_EXP_SLTSTA_DLLSC); + PCI_EXP_SLTSTA_MRLSC | PCI_EXP_SLTSTA_CC | + PCI_EXP_SLTSTA_DLLSC); ctrl_info(ctrl, "Slot #%d AttnBtn%c PwrCtrl%c MRL%c AttnInd%c PwrInd%c HotPlug%c Surprise%c Interlock%c NoCompl%c LLActRep%c\n", (slot_cap & PCI_EXP_SLTCAP_PSN) >> 19,