Implement error_resume callback in DPC so, after DPC trigger event
enumerates the devices beneath.

Signed-off-by: Oza Pawandeep <p...@codeaurora.org>

diff --git a/drivers/pci/pcie/pcie-dpc.c b/drivers/pci/pcie/pcie-dpc.c
index e15bcda..751efc0 100644
--- a/drivers/pci/pcie/pcie-dpc.c
+++ b/drivers/pci/pcie/pcie-dpc.c
@@ -126,6 +126,21 @@ static void dpc_wait_link_inactive(struct dpc_dev *dpc)
 }
 
 /**
+ * dpc_error_resume - enumerate the devices beneath
+ * @dev: pointer to Root Port's pci_dev data structure
+ *
+ * Invoked by Port Bus driver during fatal recovery.
+ */
+static void dpc_error_resume(struct pci_dev *pdev)
+{
+       if (pci_wait_for_link(pdev, true)) {
+               pci_lock_rescan_remove();
+               pci_rescan_bus(pdev->bus);
+               pci_unlock_rescan_remove();
+       }
+}
+
+/**
  * dpc_reset_link - reset link DPC  routine
  * @dev: pointer to Root Port's pci_dev data structure
  *
@@ -364,6 +379,7 @@ static void dpc_remove(struct pcie_device *dev)
        .probe          = dpc_probe,
        .remove         = dpc_remove,
        .reset_link     = dpc_reset_link,
+       .error_resume   = dpc_error_resume,
 };
 
 static int __init dpc_service_init(void)
diff --git a/drivers/pci/pcie/pcie-err.c b/drivers/pci/pcie/pcie-err.c
index 1ea4b9a..1e1bf98 100644
--- a/drivers/pci/pcie/pcie-err.c
+++ b/drivers/pci/pcie/pcie-err.c
@@ -236,6 +236,7 @@ static pci_ers_result_t reset_link(struct pci_dev *dev, int 
severity)
  * @state: error state
  * @error_mesg: message to print
  * @cb: callback to be broadcast
+ * @severity: error severity
  *
  * Invoked during error recovery process. Once being invoked, the content
  * of error severity will be broadcast to all downstream drivers in a
@@ -244,7 +245,8 @@ static pci_ers_result_t reset_link(struct pci_dev *dev, int 
severity)
 static pci_ers_result_t broadcast_error_message(struct pci_dev *dev,
        enum pci_channel_state state,
        char *error_mesg,
-       int (*cb)(struct pci_dev *, void *))
+       int (*cb)(struct pci_dev *, void *),
+       int severity)
 {
        struct aer_broadcast_data result_data;
 
@@ -256,6 +258,17 @@ static pci_ers_result_t broadcast_error_message(struct 
pci_dev *dev,
                result_data.result = PCI_ERS_RESULT_RECOVERED;
 
        if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
+               /* If DPC is triggered, call resume error handler
+                * because, at this point we can safely assume that
+                * link recovery has happened, this is only handled if
+                * callback is resume, as this function can be called
+                * with multiple callbacks.
+                */
+               if ((severity == DPC_FATAL) &&
+                   (cb == report_resume)) {
+                       cb(dev, NULL);
+                       return PCI_ERS_RESULT_RECOVERED;
+               }
                /*
                 * If the error is reported by a bridge, we think this error
                 * is related to the downstream link of the bridge, so we
@@ -305,7 +318,8 @@ void pcie_do_recovery(struct pci_dev *dev, int severity)
        status = broadcast_error_message(dev,
                        state,
                        "error_detected",
-                       report_error_detected);
+                       report_error_detected,
+                       severity);
 
        if (severity == AER_FATAL ||
            severity == DPC_FATAL) {
@@ -321,7 +335,8 @@ void pcie_do_recovery(struct pci_dev *dev, int severity)
                status = broadcast_error_message(dev,
                                state,
                                "mmio_enabled",
-                               report_mmio_enabled);
+                               report_mmio_enabled,
+                               severity);
 
        if (status == PCI_ERS_RESULT_NEED_RESET) {
                /*
@@ -332,7 +347,8 @@ void pcie_do_recovery(struct pci_dev *dev, int severity)
                status = broadcast_error_message(dev,
                                state,
                                "slot_reset",
-                               report_slot_reset);
+                               report_slot_reset,
+                               severity);
        }
 
        if (status != PCI_ERS_RESULT_RECOVERED)
@@ -342,7 +358,8 @@ void pcie_do_recovery(struct pci_dev *dev, int severity)
        broadcast_error_message(dev,
                                state,
                                "resume",
-                               report_resume);
+                               report_resume,
+                               severity);
 
        dev_info(&dev->dev, "Device recovery successful\n");
        mutex_unlock(&pci_err_recovery_lock);
-- 
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm 
Technologies, Inc.,
a Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux 
Foundation Collaborative Project.

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