[PATCH v9 12/14] PCI: Provide stub failed link recovery for device probing and hot plug

Maciej W. Rozycki macro at orcam.me.uk
Mon Jun 12 03:20:02 AEST 2023


This now fails unconditionally and will be always optimised away, but 
provides for quirks to implement recovery for failed links detected in 
device probing and device hot plug events.

Signed-off-by: Maciej W. Rozycki <macro at orcam.me.uk>
---
New change in v9, factored out from 7/7:

- Rename `pcie_downstream_link_retrain' to `pcie_failed_link_retrain'.

- Add stub implementation in "pci.h".
---
 drivers/pci/pci.c   |    2 ++
 drivers/pci/pci.h   |    4 ++++
 drivers/pci/probe.c |    2 ++
 3 files changed, 8 insertions(+)

linux-pcie-failed-link-retrain.diff
Index: linux-macro/drivers/pci/pci.c
===================================================================
--- linux-macro.orig/drivers/pci/pci.c
+++ linux-macro/drivers/pci/pci.c
@@ -4912,6 +4912,8 @@ static bool pcie_wait_for_link_delay(str
 	if (active)
 		msleep(20);
 	ret = pcie_wait_for_link_status(pdev, false, active);
+	if (active && !ret)
+		ret = pcie_failed_link_retrain(pdev);
 	if (active && ret)
 		msleep(delay);
 
Index: linux-macro/drivers/pci/pci.h
===================================================================
--- linux-macro.orig/drivers/pci/pci.h
+++ linux-macro/drivers/pci/pci.h
@@ -554,6 +554,10 @@ static inline int pci_dev_specific_disab
 	return -ENOTTY;
 }
 #endif
+static inline bool pcie_failed_link_retrain(struct pci_dev *dev)
+{
+	return false;
+}
 
 /* PCI error reporting and recovery */
 pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
Index: linux-macro/drivers/pci/probe.c
===================================================================
--- linux-macro.orig/drivers/pci/probe.c
+++ linux-macro/drivers/pci/probe.c
@@ -2549,6 +2549,8 @@ void pci_device_add(struct pci_dev *dev,
 	dma_set_max_seg_size(&dev->dev, 65536);
 	dma_set_seg_boundary(&dev->dev, 0xffffffff);
 
+	pcie_failed_link_retrain(dev);
+
 	/* Fix up broken headers */
 	pci_fixup_device(pci_fixup_header, dev);
 


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