From: Bjorn Helgaas <helgaas@kernel.org>
To: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
ashok.raj@intel.com, Keith Busch <keith.busch@intel.com>,
Huong Nguyen <huong.nguyen@dell.com>,
Austin Bolen <Austin.Bolen@dell.com>
Subject: Re: [PATCH v13 4/8] PCI/DPC: Add Error Disconnect Recover (EDR) support
Date: Mon, 27 Jan 2020 07:50:17 -0600 [thread overview]
Message-ID: <20200127135017.GA260782@google.com> (raw)
In-Reply-To: <20200125232500.GA112031@skuppusw-desk.amr.corp.intel.com>
On Sat, Jan 25, 2020 at 03:25:00PM -0800, Kuppuswamy Sathyanarayanan wrote:
> On Fri, Jan 24, 2020 at 09:04:50AM -0600, Bjorn Helgaas wrote:
> > On Sat, Jan 18, 2020 at 08:00:33PM -0800, sathyanarayanan.kuppuswamy@linux.intel.com wrote:
> > > From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> > >
> > > As per ACPI specification r6.3, sec 5.6.6, when firmware owns Downstream
> > > Port Containment (DPC), its expected to use the "Error Disconnect
> > > Recover" (EDR) notification to alert OSPM of a DPC event and if OS
> > > supports EDR, its expected to handle the software state invalidation and
> > > port recovery in OS, and also let firmware know the recovery status via
> > > _OST ACPI call. Related _OST status codes can be found in ACPI
> > > specification r6.3, sec 6.3.5.2.
> > >
> > > Also, as per PCI firmware specification r3.2 Downstream Port Containment
> > > Related Enhancements ECN, sec 4.5.1, table 4-6, If DPC is controlled by
> > > firmware (firmware first mode), firmware is responsible for
> > > configuring the DPC and OS is responsible for error recovery. Also, OS
> > > is allowed to modify DPC registers only during the EDR notification
> > > window. So with EDR support, OS should provide DPC port services even in
> > > firmware first mode.
> ...
> > > + acpi_status astatus;
> > > +
> > > + dpc->adev = adev;
> > > +
> > > + astatus = acpi_install_notify_handler(adev->handle,
> > > + ACPI_SYSTEM_NOTIFY,
> > > + edr_handle_event,
> > > + dpc);
> >
> > I think there are a couple issues with the ECN here:
> >
> > - The ECN allows EDR notifications on host bridges (sec 4.5.1, table
> > 4-4), but it does not allow the "Locate" _DSM under host bridges
> > (sec 4.6.13).
> >
> > - The ECN allows EDR notifications on root ports or switch ports
> > that do not support DPC (sec 4.5.1), but it does not allow the
> > "Locate" _DSM on those ports (sec 4.6.13).
>
> Can you please give more details on where its mentioned? Following is
> the copy of "Locate" _DSM location related specification. All it says is,
> this object can be placed under any object representing root port or
> switch port. It does not seem to add any restrictions. Please let me know
> your comments.
>
> Location:
> This object can be placed under any object representing a DPC capable
> PCI Express Root Port or Switch Downstream Port. If a port implements
> this DSM, its child devices cannot instantiate this DSM function
You quoted it: "This object [the 'Locate' _DSM] can be placed under
any object representing a *DPC capable* PCI Express Root Port or Switch
Downstream Port."
If the intention was to allow the Locate _DSM for *any* root ports or
switch downstream ports, the spec should not include the "DPC capable"
restriction.
Bjorn
next prev parent reply other threads:[~2020-01-27 13:50 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-19 4:00 [PATCH v13 0/8] Add Error Disconnect Recover (EDR) support sathyanarayanan.kuppuswamy
2020-01-19 4:00 ` [PATCH v13 1/8] PCI/ERR: Update error status after reset_link() sathyanarayanan.kuppuswamy
2020-02-05 18:28 ` Kuppuswamy Sathyanarayanan
2020-02-05 19:03 ` Bjorn Helgaas
2020-01-19 4:00 ` [PATCH v13 2/8] PCI/DPC: Allow dpc_probe() even if firmware first mode is enabled sathyanarayanan.kuppuswamy
2020-01-22 23:17 ` Bjorn Helgaas
2020-01-23 0:42 ` Kuppuswamy Sathyanarayanan
2020-01-23 3:10 ` Bjorn Helgaas
2020-01-23 18:04 ` Kuppuswamy Sathyanarayanan
2020-01-19 4:00 ` [PATCH v13 3/8] PCI/DPC: Add dpc_process_error() wrapper function sathyanarayanan.kuppuswamy
2020-01-19 4:00 ` [PATCH v13 4/8] PCI/DPC: Add Error Disconnect Recover (EDR) support sathyanarayanan.kuppuswamy
2020-01-24 15:04 ` Bjorn Helgaas
2020-01-25 23:25 ` Kuppuswamy Sathyanarayanan
2020-01-27 13:50 ` Bjorn Helgaas [this message]
2020-01-19 4:00 ` [PATCH v13 5/8] PCI/AER: Allow clearing Error Status Register in FF mode sathyanarayanan.kuppuswamy
2020-01-19 4:00 ` [PATCH v13 6/8] PCI/DPC: Update comments related to DPC recovery on NON_FATAL errors sathyanarayanan.kuppuswamy
2020-01-19 4:00 ` [PATCH v13 7/8] PCI/DPC: Clear AER registers in EDR mode sathyanarayanan.kuppuswamy
2020-01-19 4:00 ` [PATCH v13 8/8] PCI/ACPI: Enable EDR support sathyanarayanan.kuppuswamy
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