netdev - [PATCH net-next 4/4] pds_core: add attempts to fix broken PCI

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Date: Thu, 14 Sep 2023 15:32:00 -0700
From: Shannon Nelson <shannon.nelson@....com>
To: <netdev@...r.kernel.org>, <brett.creeley@....com>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>
CC: Shannon Nelson <shannon.nelson@....com>
Subject: [PATCH net-next 4/4] pds_core: add attempts to fix broken PCI

If we see a 0xff value from a PCI register read, we know that
the PCI connection is broken, possibly by a low level reset that
didn't go through the nice pci_error_handlers path.

Make use of the PCI cleanup code that we already have from the
reset handlers and add some detection and attempted recovery
from a broken PCI connection.

Signed-off-by: Shannon Nelson <shannon.nelson@....com>
Reviewed-by: Brett Creeley <brett.creeley@....com>
---
 drivers/net/ethernet/amd/pds_core/core.c | 14 ++++++++++++++
 drivers/net/ethernet/amd/pds_core/core.h |  3 +++
 drivers/net/ethernet/amd/pds_core/main.c |  4 ++--
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/amd/pds_core/core.c b/drivers/net/ethernet/amd/pds_core/core.c
index c1b6b5f7c0b5..2a8643e167e1 100644
--- a/drivers/net/ethernet/amd/pds_core/core.c
+++ b/drivers/net/ethernet/amd/pds_core/core.c
@@ -578,6 +578,18 @@ void pdsc_fw_up(struct pdsc *pdsc)
 	pdsc_teardown(pdsc, PDSC_TEARDOWN_RECOVERY);
 }
 
+static void pdsc_check_pci_health(struct pdsc *pdsc)
+{
+	u8 fw_status = ioread8(&pdsc->info_regs->fw_status);
+
+	/* is PCI broken? */
+	if (fw_status != PDS_RC_BAD_PCI)
+		return;
+
+	pdsc_reset_prepare(pdsc->pdev);
+	pdsc_reset_done(pdsc->pdev);
+}
+
 void pdsc_health_thread(struct work_struct *work)
 {
 	struct pdsc *pdsc = container_of(work, struct pdsc, health_work);
@@ -604,6 +616,8 @@ void pdsc_health_thread(struct work_struct *work)
 			pdsc_fw_down(pdsc);
 	}
 
+	pdsc_check_pci_health(pdsc);
+
 	pdsc->fw_generation = pdsc->fw_status & PDS_CORE_FW_STS_F_GENERATION;
 
 out_unlock:
diff --git a/drivers/net/ethernet/amd/pds_core/core.h b/drivers/net/ethernet/amd/pds_core/core.h
index 19c1957167da..f3a7deda9972 100644
--- a/drivers/net/ethernet/amd/pds_core/core.h
+++ b/drivers/net/ethernet/amd/pds_core/core.h
@@ -283,6 +283,9 @@ int pdsc_devcmd_reset(struct pdsc *pdsc);
 int pdsc_dev_reinit(struct pdsc *pdsc);
 int pdsc_dev_init(struct pdsc *pdsc);
 
+void pdsc_reset_prepare(struct pci_dev *pdev);
+void pdsc_reset_done(struct pci_dev *pdev);
+
 int pdsc_intr_alloc(struct pdsc *pdsc, char *name,
 		    irq_handler_t handler, void *data);
 void pdsc_intr_free(struct pdsc *pdsc, int index);
diff --git a/drivers/net/ethernet/amd/pds_core/main.c b/drivers/net/ethernet/amd/pds_core/main.c
index 4c7f982c12a1..3080898d7b95 100644
--- a/drivers/net/ethernet/amd/pds_core/main.c
+++ b/drivers/net/ethernet/amd/pds_core/main.c
@@ -445,7 +445,7 @@ static void pdsc_remove(struct pci_dev *pdev)
 	devlink_free(dl);
 }
 
-static void pdsc_reset_prepare(struct pci_dev *pdev)
+void pdsc_reset_prepare(struct pci_dev *pdev)
 {
 	struct pdsc *pdsc = pci_get_drvdata(pdev);
 
@@ -457,7 +457,7 @@ static void pdsc_reset_prepare(struct pci_dev *pdev)
 	pci_disable_device(pdev);
 }
 
-static void pdsc_reset_done(struct pci_dev *pdev)
+void pdsc_reset_done(struct pci_dev *pdev)
 {
 	struct pdsc *pdsc = pci_get_drvdata(pdev);
 	struct device *dev = pdsc->dev;
-- 
2.17.1