[PATCH v4 31/63] Documentation: PCI: convert pci-error-recovery.txt to reST

Changbin Du
2019-04-23T16:35:40Z

This converts the plain text documentation to reStructuredText format and
add it to Sphinx TOC tree. No essential content change.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
---
Documentation/PCI/index.rst | 1 +
...or-recovery.txt => pci-error-recovery.rst} | 178 +++++++++---------
MAINTAINERS | 2 +-
3 files changed, 94 insertions(+), 87 deletions(-)
rename Documentation/PCI/{pci-error-recovery.txt => pci-error-recovery.rst} (80%)

diff --git a/Documentation/PCI/index.rst b/Documentation/PCI/index.rst
index c877a369481d..5ee4dba07116 100644
--- a/Documentation/PCI/index.rst
+++ b/Documentation/PCI/index.rst
@@ -13,3 +13,4 @@ Linux PCI Bus Subsystem
pci-iov-howto
MSI-HOWTO
acpi-info
+ pci-error-recovery
diff --git a/Documentation/PCI/pci-error-recovery.txt b/Documentation/PCI/pci-error-recovery.rst
similarity index 80%
rename from Documentation/PCI/pci-error-recovery.txt
rename to Documentation/PCI/pci-error-recovery.rst
index 0b6bb3ef449e..533ec4035bf5 100644
--- a/Documentation/PCI/pci-error-recovery.txt
+++ b/Documentation/PCI/pci-error-recovery.rst
@@ -1,12 +1,13 @@
+.. SPDX-License-Identifier: GPL-2.0

- PCI Error Recovery
- ------------------
- February 2, 2006
+==================
+PCI Error Recovery
+==================

- Current document maintainer:
- Linas Vepstas <linasvepstas@gmail.com>
- updated by Richard Lary <rlary@us.ibm.com>
- and Mike Mason <mmlnx@us.ibm.com> on 27-Jul-2009
+
+:Authors: - Linas Vepstas <linasvepstas@gmail.com>
+ - Richard Lary <rlary@us.ibm.com>
+ - Mike Mason <mmlnx@us.ibm.com>

Many PCI bus controllers are able to detect a variety of hardware
@@ -63,7 +64,8 @@ mechanisms for dealing with SCSI bus errors and SCSI bus resets.

Detailed Design
----------------
+===============
+
Design and implementation details below, based on a chain of
public email discussions with Ben Herrenschmidt, circa 5 April 2005.

@@ -73,30 +75,33 @@ pci_driver. A driver that fails to provide the structure is "non-aware",
and the actual recovery steps taken are platform dependent. The
arch/powerpc implementation will simulate a PCI hotplug remove/add.

-This structure has the form:
-struct pci_error_handlers
-{
- int (*error_detected)(struct pci_dev *dev, enum pci_channel_state);
- int (*mmio_enabled)(struct pci_dev *dev);
- int (*slot_reset)(struct pci_dev *dev);
- void (*resume)(struct pci_dev *dev);
-};
-
-The possible channel states are:
-enum pci_channel_state {
- pci_channel_io_normal, /* I/O channel is in normal state */
- pci_channel_io_frozen, /* I/O to channel is blocked */
- pci_channel_io_perm_failure, /* PCI card is dead */
-};
-
-Possible return values are:
-enum pci_ers_result {
- PCI_ERS_RESULT_NONE, /* no result/none/not supported in device driver */
- PCI_ERS_RESULT_CAN_RECOVER, /* Device driver can recover without slot reset */
- PCI_ERS_RESULT_NEED_RESET, /* Device driver wants slot to be reset. */
- PCI_ERS_RESULT_DISCONNECT, /* Device has completely failed, is unrecoverable */
- PCI_ERS_RESULT_RECOVERED, /* Device driver is fully recovered and operational */
-};
+This structure has the form::
+
+ struct pci_error_handlers
+ {
+ int (*error_detected)(struct pci_dev *dev, enum pci_channel_state);
+ int (*mmio_enabled)(struct pci_dev *dev);
+ int (*slot_reset)(struct pci_dev *dev);
+ void (*resume)(struct pci_dev *dev);
+ };
+
+The possible channel states are::
+
+ enum pci_channel_state {
+ pci_channel_io_normal, /* I/O channel is in normal state */
+ pci_channel_io_frozen, /* I/O to channel is blocked */
+ pci_channel_io_perm_failure, /* PCI card is dead */
+ };
+
+Possible return values are::
+
+ enum pci_ers_result {
+ PCI_ERS_RESULT_NONE, /* no result/none/not supported in device driver */
+ PCI_ERS_RESULT_CAN_RECOVER, /* Device driver can recover without slot reset */
+ PCI_ERS_RESULT_NEED_RESET, /* Device driver wants slot to be reset. */
+ PCI_ERS_RESULT_DISCONNECT, /* Device has completely failed, is unrecoverable */
+ PCI_ERS_RESULT_RECOVERED, /* Device driver is fully recovered and operational */
+ };

A driver does not have to implement all of these callbacks; however,
if it implements any, it must implement error_detected(). If a callback
@@ -134,16 +139,17 @@ 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_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
- a chance to extract some diagnostic information (see
- mmio_enable, below).
- - PCI_ERS_RESULT_NEED_RESET:
- Driver returns this if it can't recover without a
- slot reset.
- - PCI_ERS_RESULT_DISCONNECT:
- Driver returns this if it doesn't want to recover at all.
+
+ - 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
+ a chance to extract some diagnostic information (see
+ mmio_enable, below).
+ - PCI_ERS_RESULT_NEED_RESET:
+ Driver returns this if it can't recover without a
+ slot reset.
+ - PCI_ERS_RESULT_DISCONNECT:
+ Driver returns this if it doesn't want to recover at all.

The next step taken will depend on the result codes returned by the
drivers.
@@ -177,7 +183,7 @@ is STEP 6 (Permanent Failure).
>>> get the device working again.

STEP 2: MMIO Enabled
--------------------
+--------------------
The platform re-enables MMIO to the device (but typically not the
DMA), and then calls the mmio_enabled() callback on all affected
device drivers.
@@ -203,23 +209,23 @@ instead will have gone directly to STEP 3 (Link Reset) or STEP 4 (Slot Reset)
>>> into one of the next states, that is, link reset or slot reset.

The driver should return one of the following result codes:
- - PCI_ERS_RESULT_RECOVERED
- Driver returns this if it thinks the device is fully
- functional and thinks it is ready to start
- normal driver operations again. There is no
- guarantee that the driver will actually be
- allowed to proceed, as another driver on the
- same segment might have failed and thus triggered a
- slot reset on platforms that support it.
-
- - PCI_ERS_RESULT_NEED_RESET
- Driver returns this if it thinks the device is not
- recoverable in its current state and it needs a slot
- reset to proceed.
-
- - PCI_ERS_RESULT_DISCONNECT
- Same as above. Total failure, no recovery even after
- reset driver dead. (To be defined more precisely)
+ - PCI_ERS_RESULT_RECOVERED
+ Driver returns this if it thinks the device is fully
+ functional and thinks it is ready to start
+ normal driver operations again. There is no
+ guarantee that the driver will actually be
+ allowed to proceed, as another driver on the
+ same segment might have failed and thus triggered a
+ slot reset on platforms that support it.
+
+ - PCI_ERS_RESULT_NEED_RESET
+ Driver returns this if it thinks the device is not
+ recoverable in its current state and it needs a slot
+ reset to proceed.
+
+ - PCI_ERS_RESULT_DISCONNECT
+ Same as above. Total failure, no recovery even after
+ reset driver dead. (To be defined more precisely)

The next step taken depends on the results returned by the drivers.
If all drivers returned PCI_ERS_RESULT_RECOVERED, then the platform
@@ -293,24 +299,24 @@ device will be considered "dead" in this case.
Drivers for multi-function cards will need to coordinate among
themselves as to which driver instance will perform any "one-shot"
or global device initialization. For example, the Symbios sym53cxx2
-driver performs device init only from PCI function 0:
+driver performs device init only from PCI function 0::

-+ if (PCI_FUNC(pdev->devfn) == 0)
-+ sym_reset_scsi_bus(np, 0);
+ + if (PCI_FUNC(pdev->devfn) == 0)
+ + sym_reset_scsi_bus(np, 0);

- Result codes:
- - PCI_ERS_RESULT_DISCONNECT
- Same as above.
+Result codes:
+ - PCI_ERS_RESULT_DISCONNECT
+ Same as above.

Drivers for PCI Express cards that require a fundamental reset must
set the needs_freset bit in the pci_dev structure in their probe function.
For example, the QLogic qla2xxx driver sets the needs_freset bit for certain
-PCI card types:
+PCI card types::

-+ /* Set EEH reset type to fundamental if required by hba */
-+ if (IS_QLA24XX(ha) || IS_QLA25XX(ha) || IS_QLA81XX(ha))
-+ pdev->needs_freset = 1;
-+
+ + /* Set EEH reset type to fundamental if required by hba */
+ + if (IS_QLA24XX(ha) || IS_QLA25XX(ha) || IS_QLA81XX(ha))
+ + pdev->needs_freset = 1;
+ +

Platform proceeds either to STEP 5 (Resume Operations) or STEP 6 (Permanent
Failure).
@@ -370,23 +376,23 @@ The current policy is to turn this into a platform policy.
That is, the recovery API only requires that:

- There is no guarantee that interrupt delivery can proceed from any
-device on the segment starting from the error detection and until the
-slot_reset callback is called, at which point interrupts are expected
-to be fully operational.
+ device on the segment starting from the error detection and until the
+ slot_reset callback is called, at which point interrupts are expected
+ to be fully operational.

- There is no guarantee that interrupt delivery is stopped, that is,
-a driver that gets an interrupt after detecting an error, or that detects
-an error within the interrupt handler such that it prevents proper
-ack'ing of the interrupt (and thus removal of the source) should just
-return IRQ_NOTHANDLED. It's up to the platform to deal with that
-condition, typically by masking the IRQ source during the duration of
-the error handling. It is expected that the platform "knows" which
-interrupts are routed to error-management capable slots and can deal
-with temporarily disabling that IRQ number during error processing (this
-isn't terribly complex). That means some IRQ latency for other devices
-sharing the interrupt, but there is simply no other way. High end
-platforms aren't supposed to share interrupts between many devices
-anyway :)
+ a driver that gets an interrupt after detecting an error, or that detects
+ an error within the interrupt handler such that it prevents proper
+ ack'ing of the interrupt (and thus removal of the source) should just
+ return IRQ_NOTHANDLED. It's up to the platform to deal with that
+ condition, typically by masking the IRQ source during the duration of
+ the error handling. It is expected that the platform "knows" which
+ interrupts are routed to error-management capable slots and can deal
+ with temporarily disabling that IRQ number during error processing (this
+ isn't terribly complex). That means some IRQ latency for other devices
+ sharing the interrupt, but there is simply no other way. High end
+ platforms aren't supposed to share interrupts between many devices
+ anyway :)

>>> Implementation details for the powerpc platform are discussed in
>>> the file Documentation/powerpc/eeh-pci-error-recovery.txt
diff --git a/MAINTAINERS b/MAINTAINERS
index 87f930bf32ad..403178958b05 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11965,7 +11965,7 @@ M: Sam Bobroff <sbobroff@linux.ibm.com>
M: Oliver O'Halloran <oohall@gmail.com>
L: linuxppc-dev@lists.ozlabs.org
S: Supported
-F: Documentation/PCI/pci-error-recovery.txt
+F: Documentation/PCI/pci-error-recovery.rst
F: drivers/pci/pcie/aer.c
F: drivers/pci/pcie/dpc.c
F: drivers/pci/pcie/err.c
--
2.20.1