From 425afcb6aa408de4522f4be7530305490fca6c04 Mon Sep 17 00:00:00 2001
From: Vasundhara Volam <vasundhara-v.volam@broadcom.com>
Date: Mon, 26 Oct 2020 00:18:19 -0400
Subject: [PATCH 8/8] bnxt_en: Re-write PCI BARs after PCI fatal error.
Git-commit: f75d9a0aa96721d20011cd5f8c7a24eb32728589
Patch-mainline: v5.10-rc2
References: git-fixes

When a PCIe fatal error occurs, the internal latched BAR addresses
in the chip get reset even though the BAR register values in config
space are retained.

pci_restore_state() will not rewrite the BAR addresses if the
BAR address values are valid, causing the chip's internal BAR addresses
to stay invalid.  So we need to zero the BAR registers during PCIe fatal
error to force pci_restore_state() to restore the BAR addresses.  These
write cycles to the BAR registers will cause the proper BAR addresses to
latch internally.

Fixes: 6316ea6db93d ("bnxt_en: Enable AER support.")
Signed-off-by: Vasundhara Volam <vasundhara-v.volam@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 19 ++++++++++++++++++-
 drivers/net/ethernet/broadcom/bnxt/bnxt.h |  1 +
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index b1dbacc8d6d5..b1ba6df8911d 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -10857,6 +10857,9 @@ static pci_ers_result_t bnxt_io_error_detected(struct pci_dev *pdev,
 		return PCI_ERS_RESULT_DISCONNECT;
 	}
 
+	if (state == pci_channel_io_frozen)
+		set_bit(BNXT_STATE_PCI_CHANNEL_IO_FROZEN, &bp->state);
+
 	if (netif_running(netdev))
 		bnxt_close(netdev);
 
@@ -10884,7 +10887,7 @@ static pci_ers_result_t bnxt_io_slot_reset(struct pci_dev *pdev)
 {
 	struct net_device *netdev = pci_get_drvdata(pdev);
 	struct bnxt *bp = netdev_priv(netdev);
-	int err = 0;
+	int err = 0, off;
 	pci_ers_result_t result = PCI_ERS_RESULT_DISCONNECT;
 
 	netdev_info(bp->dev, "PCI Slot Reset\n");
@@ -10896,6 +10899,20 @@ static pci_ers_result_t bnxt_io_slot_reset(struct pci_dev *pdev)
 			"Cannot re-enable PCI device after reset.\n");
 	} else {
 		pci_set_master(pdev);
+		/* Upon fatal error, our device internal logic that latches to
+		 * BAR value is getting reset and will restore only upon
+		 * rewritting the BARs.
+		 *
+		 * As pci_restore_state() does not re-write the BARs if the
+		 * value is same as saved value earlier, driver needs to
+		 * write the BARs to 0 to force restore, in case of fatal error.
+		 */
+		if (test_and_clear_bit(BNXT_STATE_PCI_CHANNEL_IO_FROZEN,
+				       &bp->state)) {
+			for (off = PCI_BASE_ADDRESS_0;
+			     off <= PCI_BASE_ADDRESS_5; off += 4)
+				pci_write_config_dword(bp->pdev, off, 0);
+		}
 		pci_restore_state(pdev);
 		pci_save_state(pdev);
 
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index a2d616f1aaeb..11dc51e82fd6 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -1462,6 +1462,7 @@ struct bnxt {
 #define BNXT_STATE_OPEN		0
 #define BNXT_STATE_IN_SP_TASK	1
 #define BNXT_STATE_READ_STATS	2
+#define BNXT_STATE_PCI_CHANNEL_IO_FROZEN	8
 
 	struct bnxt_irq	*irq_tbl;
 	int			total_irqs;
-- 
2.16.4