Re: [PATCH v2 5/5] drivers/pci/hotplug: Support surprise hotplug in powernv driver

On Mon, Sep 26, 2016 at 10:56:07PM +1000, Gavin Shan wrote:

This supports PCI surprise hotplug. The design is highlighted as
below:

  * The PCI slot's surprise hotplug capability is exposed through
    device node property "ibm,slot-surprise-pluggable", meaning
    PCI surprise hotplug will be disabled if skiboot doesn't support
    it yet.
  * The interrupt because of presence or link state change is raised
    on surprise hotplug event. One event is allocated and queued to
    the PCI slot for workqueue to pick it up and process in serialized
    fashion. The code flow for surprise hotplug is same to that for
    managed hotplug except: the affected PEs are put into frozen state
    to avoid unexpected EEH error reporting in surprise hot remove path.

Signed-off-by: Gavin Shan <redacted>
---

.../...

+static irqreturn_t pnv_php_interrupt(int irq, void *data)
+{
+	struct pnv_php_slot *php_slot = data;
+	struct pci_dev *pchild, *pdev = php_slot->pdev;
+	struct eeh_dev *edev;
+	struct eeh_pe *pe;
+	struct pnv_php_event *event;
+	u16 sts, lsts;
+	u8 presence;
+	bool added;
+	unsigned long flags;
+	int ret;
+
+	pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &sts);
+	sts &= (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC);
+	pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, sts);
+	if (sts & PCI_EXP_SLTSTA_DLLSC) {
+		pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lsts);
+		added = !!(lsts & PCI_EXP_LNKSTA_DLLLA);
+	} else if (sts & PCI_EXP_SLTSTA_PDC) {
+		ret = pnv_pci_get_presence_state(php_slot->id, &presence);
+		if (!ret)
+			return IRQ_HANDLED;
+		added = !!(presence == OPAL_PCI_SLOT_PRESENT);
+	} else {
+		return IRQ_NONE;
+	}
+
+	/* Freeze the removed PE to avoid unexpected error reporting */
+	if (!added) {
+		pchild = list_first_entry_or_null(&php_slot->bus->devices,
+						  struct pci_dev, bus_list);
+		edev = pchild ? pci_dev_to_eeh_dev(pchild) : NULL;
+		pe = edev ? edev->pe : NULL;
+		if (pe) {
+			eeh_serialize_lock(&flags);
+			eeh_pe_state_mark(pe, EEH_PE_ISOLATED);
+			eeh_serialize_unlock(flags);
+			eeh_pe_set_option(pe, EEH_OPT_FREEZE_PE);
+		}
+	}
+

I still need export @confirm_error_lock. Otherwise, it will be failed to be
built when having CONFIG_HOTPLUG_PCI_POWERNV=m. I will respin and add one
patch for that in v3.

Thanks,
Gavin