The "Downstream Port Containment related Enhancements" ECN of Jan 28, 2019
(document 12888 below), defined the EDR_PORT_LOCATE_DSM function with
Revision ID 5 with a return value encoding (Bits 2:0 = Function, Bits 7:3 =
Device, Bits 15:8 = Bus). When the ECN was integrated into PCI Firmware
r3.3, sec 4.6.13, Bit 31 was added to indicate success or failure.
Check Bit 31 for failure in acpi_dpc_port_get().
Link: https://lore.kernel.org/r/20240501022543.1626025-1-sathyanarayanan.kuppuswamy@linux.intel.com
Link: https://members.pcisig.com/wg/PCI-SIG/document/12888
Fixes: ac1c8e35a3 ("PCI/DPC: Add Error Disconnect Recover (EDR) support")
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
[bhelgaas: split into two patches, update commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Satish Thatchanamurthy <Satish.Thatchanamurt@Dell.com> # one platform
The "Downstream Port Containment related Enhancements" ECN of Jan 28, 2019
(document 12888 below), defined the EDR_PORT_DPC_ENABLE_DSM function with
Revision ID 5 with Arg3 being an integer. But when the ECN was integrated
into PCI Firmware r3.3, sec 4.6.12, it was defined as Revision ID 6 with
Arg3 being a package containing an integer.
The implementation in acpi_enable_dpc() supplies a package as Arg3 (arg4 in
the code), but it previously specified Revision ID 5. Align this with PCI
Firmware r3.3 by using Revision ID 6.
If firmware implemented per the ECN, its Revision 5 function would receive
a package as Arg3 when it expects an integer, so acpi_enable_dpc() would
likely fail. If such firmware exists and lacks a Revision 6 function that
expects a package, we may have to add support for Revision 5.
Link: https://lore.kernel.org/r/20240501022543.1626025-1-sathyanarayanan.kuppuswamy@linux.intel.com
Link: https://members.pcisig.com/wg/PCI-SIG/document/12888
Fixes: ac1c8e35a3 ("PCI/DPC: Add Error Disconnect Recover (EDR) support")
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
[bhelgaas: split into two patches, update commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Satish Thatchanamurthy <Satish.Thatchanamurt@Dell.com> # one platform
EDR documentation is a bit sketchy. Add a couple comments to
edr_handle_event() about the devices involved.
Link: https://lore.kernel.org/r/20230407215259.GA3825733@bhelgaas
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
During EDR recovery, the OS must clear error status of the port that
triggered DPC even if firmware retains control of DPC and AER (see the
implementation note in the PCI Firmware spec r3.3, sec 4.6.12).
Prior to 068c29a248 ("PCI/ERR: Clear PCIe Device Status errors only if
OS owns AER"), the port Device Status was cleared in this path:
edr_handle_event
dpc_process_error(dev) # "dev" triggered DPC
pcie_do_recovery(dev, dpc_reset_link)
dpc_reset_link # exit DPC
pcie_clear_device_status(dev) # clear Device Status
After 068c29a248, pcie_do_recovery() no longer clears Device Status when
firmware controls AER, so the error bit remains set even after recovery.
Per the "Downstream Port Containment configuration control" bit in the
returned _OSC Control Field (sec 4.5.1), the OS is allowed to clear error
status until it evaluates _OST, so clear Device Status in
edr_handle_event() if the error recovery was successful.
[bhelgaas: commit log]
Fixes: 068c29a248 ("PCI/ERR: Clear PCIe Device Status errors only if OS owns AER")
Link: https://lore.kernel.org/r/20230315235449.1279209-1-sathyanarayanan.kuppuswamy@linux.intel.com
Reported-by: Tsaur Erwin <erwin.tsaur@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Error Disconnect Recover (EDR) is a feature that allows ACPI firmware to
notify OSPM that a device has been disconnected due to an error condition
(ACPI v6.3, sec 5.6.6). OSPM advertises its support for EDR on PCI devices
via _OSC (see [1], sec 4.5.1, table 4-4). The OSPM EDR notify handler
should invalidate software state associated with disconnected devices and
may attempt to recover them. OSPM communicates the status of recovery to
the firmware via _OST (sec 6.3.5.2).
For PCIe, firmware may use Downstream Port Containment (DPC) to support
EDR. Per [1], sec 4.5.1, table 4-6, even if firmware has retained control
of DPC, OSPM may read/write DPC control and status registers during the EDR
notification processing window, i.e., from the time it receives an EDR
notification until it clears the DPC Trigger Status.
Note that per [1], sec 4.5.1 and 4.5.2.4,
1. If the OS supports EDR, it should advertise that to firmware by
setting OSC_PCI_EDR_SUPPORT in _OSC Support.
2. If the OS sets OSC_PCI_EXPRESS_DPC_CONTROL in _OSC Control to request
control of the DPC capability, it must also set OSC_PCI_EDR_SUPPORT in
_OSC Support.
Add an EDR notify handler to attempt recovery.
[1] Downstream Port Containment Related Enhancements ECN, Jan 28, 2019,
affecting PCI Firmware Specification, Rev. 3.2
https://members.pcisig.com/wg/PCI-SIG/document/12888
[bhelgaas: squash add/enable patches into one]
Link: https://lore.kernel.org/r/90f91fe6d25c13f9d2255d2ce97ca15be307e1bb.1585000084.git.sathyanarayanan.kuppuswamy@linux.intel.com
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
