[PATCH RFC v2 3/5] PCI/DPC: Add pci_dpc_wait_recovery()
COOLING9d
From: Abhin Parekadan Jose <hidden>
Date: 2026-09-27 16:55:23
Also in:
linux-pci, lkml
Subsystem:
pci enhanced error handling (eeh) for powerpc, pci subsystem, the rest · Maintainers:
Mahesh J Salgaonkar, Bjorn Helgaas, Linus Torvalds
Revision v2 of 4 in this series.
Revisions (4)
- rfc [diff vs current]
- v2 current
- v3 [diff vs current]
- v4 [diff vs current]
pci_dpc_recovered() awaits completion of DPC recovery and then tells whether DPC recovered successfully, using test_and_clear_bit() on PCI_DPC_RECOVERED. The answer is one-shot: only the first caller sees true. Split pci_dpc_recovered() into: - pci_dpc_hp_sync_supported(), the check whether hotplug can synchronize with DPC at all. - dpc_wait_completed(), the wait for recovery with its 4 second timeout; - the final test_and_clear_bit(). Add pci_dpc_wait_recovery(), which does the check and the wait but leaves PCI_DPC_RECOVERED alone. No functional change intended. Signed-off-by: Abhin Parekadan Jose <redacted> Assisted-by: LLM --- drivers/pci/pci.h | 2 ++ drivers/pci/pcie/dpc.c | 54 ++++++++++++++++++++++++++++++++---------- 2 files changed, 44 insertions(+), 12 deletions(-)
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 2e113806f9f95..ad98e2d9289ea 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h@@ -940,12 +940,14 @@ void pci_restore_dpc_state(struct pci_dev *dev); void pci_dpc_init(struct pci_dev *pdev); void dpc_process_error(struct pci_dev *pdev); pci_ers_result_t dpc_reset_link(struct pci_dev *pdev); +void pci_dpc_wait_recovery(struct pci_dev *pdev); bool pci_dpc_recovered(struct pci_dev *pdev); unsigned int dpc_tlp_log_len(struct pci_dev *dev); #else static inline void pci_save_dpc_state(struct pci_dev *dev) { } static inline void pci_restore_dpc_state(struct pci_dev *dev) { } static inline void pci_dpc_init(struct pci_dev *pdev) { } +static inline void pci_dpc_wait_recovery(struct pci_dev *pdev) { } static inline bool pci_dpc_recovered(struct pci_dev *pdev) { return false; } #endif
diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index 2b779bd1d861b..a6438a7e3d9c7 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c@@ -92,15 +92,7 @@ static bool dpc_completed(struct pci_dev *pdev) return true; } -/** - * pci_dpc_recovered - whether DPC triggered and has recovered successfully - * @pdev: PCI device - * - * Return true if DPC was triggered for @pdev and has recovered successfully. - * Wait for recovery if it hasn't completed yet. Called from the PCIe hotplug - * driver to recognize and ignore Link Down/Up events caused by DPC. - */ -bool pci_dpc_recovered(struct pci_dev *pdev) +static bool pci_dpc_hp_sync_supported(struct pci_dev *pdev) { struct pci_host_bridge *host;
@@ -108,13 +100,18 @@ bool pci_dpc_recovered(struct pci_dev *pdev) return false; /* - * Synchronization between hotplug and DPC is not supported - * if DPC is owned by firmware and EDR is not enabled. - */ + * Synchronization between hotplug and DPC is only supported if DPC is owned + * by the OS, or by firmware with EDR enabled. + */ host = pci_find_host_bridge(pdev->bus); if (!host->native_dpc && !IS_ENABLED(CONFIG_PCIE_EDR)) return false; + return true; +} + +static void dpc_wait_completed(struct pci_dev *pdev) +{ /* * Need a timeout in case DPC never completes due to failure of * dpc_wait_rp_inactive(). The spec doesn't mandate a time limit,
@@ -122,6 +119,39 @@ bool pci_dpc_recovered(struct pci_dev *pdev) */ wait_event_timeout(dpc_completed_waitqueue, dpc_completed(pdev), msecs_to_jiffies(4000)); +} + +/** + * pci_dpc_wait_recovery - await completion of DPC recovery + * @pdev: PCI device + * + * Wait for recovery if DPC was triggered for @pdev and recovery hasn't + * completed yet. Unlike pci_dpc_recovered(), leave the record of a + * successful recovery in place. Called from the PCIe hotplug driver where + * it needs the link to have settled, but not the cause of a link change. + * Nothing is awaited if synchronization between hotplug and DPC is not + * supported for @pdev. + */ +void pci_dpc_wait_recovery(struct pci_dev *pdev) +{ + if (pci_dpc_hp_sync_supported(pdev)) + dpc_wait_completed(pdev); +} + +/** + * pci_dpc_recovered - whether DPC triggered and has recovered successfully + * @pdev: PCI device + * + * Return true if DPC was triggered for @pdev and has recovered successfully. + * Wait for recovery if it hasn't completed yet. Called from the PCIe hotplug + * driver to recognize and ignore Link Down/Up events caused by DPC. + */ +bool pci_dpc_recovered(struct pci_dev *pdev) +{ + if (!pci_dpc_hp_sync_supported(pdev)) + return false; + + dpc_wait_completed(pdev); return test_and_clear_bit(PCI_DPC_RECOVERED, &pdev->priv_flags); }
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2.51.1