Amend the documentation on PCI error recovery to fix minor inaccuracies
vis-à-vis the actual code:
* The documentation claims that a missing ->resume() or ->mmio_enabled()
callback always leads to recovery through reset. But none of the
implementations do this (pcie_do_recovery(), eeh_handle_normal_event(),
zpci_event_do_error_state_clear()).
Drop the claim to align the documentation with the code.
* The documentation does not list PCI_ERS_RESULT_RECOVERED as a valid
return value from ->error_detected(). But none of the implementations
forbid this and some drivers are returning it, e.g.:
drivers/bus/mhi/host/pci_generic.c
drivers/infiniband/hw/hfi1/pcie.c
Further down in the documentation it is implied that the return value is
in fact allowed:
"The platform will call the resume() callback on all affected device
drivers if all drivers on the segment have returned
PCI_ERS_RESULT_RECOVERED from one of the 3 previous callbacks."
The "3 previous callbacks" being ->error_detected(), ->mmio_enabled()
and ->slot_reset().
Add it to the valid return values for consistency.
Signed-off-by: Lukas Wunner <lu...@wunner.de>
Reviewed-by: Brian Norris <briannor...@chromium.org>
---
Documentation/PCI/pci-error-recovery.rst | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/Documentation/PCI/pci-error-recovery.rst
b/Documentation/PCI/pci-error-recovery.rst
index 42e1e78353f3..d5c661baa87f 100644
--- a/Documentation/PCI/pci-error-recovery.rst
+++ b/Documentation/PCI/pci-error-recovery.rst
@@ -108,8 +108,8 @@ A driver does not have to implement all of these callbacks;
however,
if it implements any, it must implement error_detected(). If a callback
is not implemented, the corresponding feature is considered unsupported.
For example, if mmio_enabled() and resume() aren't there, then it
-is assumed that the driver is not doing any direct recovery and requires
-a slot reset. Typically a driver will want to know about
+is assumed that the driver does not need these callbacks
+for recovery. Typically a driver will want to know about
a slot_reset().
The actual steps taken by a platform to recover from a PCI error
@@ -141,6 +141,9 @@ shouldn't do any new IOs. Called in task context. This is
sort of a
All drivers participating in this system must implement this call.
The driver must return one of the following result codes:
+ - PCI_ERS_RESULT_RECOVERED
+ Driver returns this if it thinks the device is usable despite
+ the error and does not need further intervention.
- PCI_ERS_RESULT_CAN_RECOVER
Driver returns this if it thinks it might be able to recover
the HW by just banging IOs or if it wants to be given
--
2.51.0
