Lukas Wunner 5e09895b40 Documentation: PCI: Amend error recovery doc with pci_save_state() rules
After recovering from a PCI error through reset, affected devices are in
D0_uninitialized state and need to be brought into D0_active state by
re-initializing their Config Space registers (PCIe r7.0 sec 5.3.1.1).

To facilitate that, the PCI core provides pci_restore_state() and
pci_save_state() helpers.  Document rules governing their usage.

As Bjorn notes, so far no file in "Documentation/ includes anything about
the idea of a driver using pci_save_state() to capture the state it wants
to restore after an error", even though it is a common pattern in drivers.
So that's obviously a gap that should be closed.

Reported-by: Bjorn Helgaas <helgaas@kernel.org>
Closes: https://lore.kernel.org/r/20251113161556.GA2284238@bhelgaas/
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Link: https://patch.msgid.link/077596ba70202be0e43fdad3bb9b93d356cbe4ec.1763746079.git.lukas@wunner.de
2025-11-24 16:59:10 -06:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2025-10-12 13:42:36 -07:00
2024-03-18 03:36:32 -06:00

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