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

Maciej W. Rozycki
2023-06-11T17:21:05Z

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@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);