From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
ashok.raj@intel.com, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <lenb@kernel.org>, Keith Busch <keith.busch@intel.com>,
Huong Nguyen <huong.nguyen@dell.com>,
Austin Bolen <Austin.Bolen@dell.com>
Subject: Re: [PATCH v12 8/8] PCI/ACPI: Enable EDR support
Date: Fri, 17 Jan 2020 15:04:37 -0800 [thread overview]
Message-ID: <cd68630b-a511-ade5-97ed-4ee0082b9f9e@linux.intel.com> (raw)
In-Reply-To: <20200117204115.GA126492@google.com>
On 1/17/20 12:41 PM, Bjorn Helgaas wrote:
> On Sun, Jan 12, 2020 at 02:44:02PM -0800, sathyanarayanan.kuppuswamy@linux.intel.com wrote:
>> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
>>
>> As per PCI firmware specification r3.2 Downstream Port Containment
>> Related Enhancements ECN, sec 4.5.1, OS must implement following steps
>> to enable/use EDR feature.
>>
>> 1. OS can use bit 7 of _OSC Control Field to negotiate control over
>> Downstream Port Containment (DPC) configuration of PCIe port. After _OSC
>> negotiation, firmware will Set this bit to grant OS control over PCIe
>> DPC configuration and Clear it if this feature was requested and denied,
>> or was not requested.
>>
>> 2. Also, if OS supports EDR, it should expose its support to BIOS by
>> setting bit 7 of _OSC Support Field. And if OS sets bit 7 of _OSC
>> Control Field it must also expose support for EDR by setting bit 7 of
>> _OSC Support Field.
>> --- a/drivers/pci/pcie/portdrv_core.c
>> +++ b/drivers/pci/pcie/portdrv_core.c
>> @@ -253,10 +253,13 @@ static int get_port_device_capability(struct pci_dev *dev)
>> /*
>> * With dpc-native, allow Linux to use DPC even if it doesn't have
>> * permission to use AER.
>> + * If EDR support is enabled in OS, then even if AER is not handled in
>> + * OS, DPC service can be enabled.
> Can you clarify this comment? It talks about AER, but the code you
> added:
Previously with condition
(pci_aer_available() && (pcie_ports_dpc_native || (services &
PCIE_PORT_SERVICE_AER)))
we have only checked whether AER is enabled and supported before
enabling DPC.
But with EDR support, we enumerate DPC driver even if AER is not
supported or handled
in OS. And the or condition (IS_ENABLED(CONFIG_PCIE_EDR) &&
!host->native_dpc) adds this
support.
> (IS_ENABLED(CONFIG_PCIE_EDR) && !host->native_dpc)
>
> doesn't have anything to do with AER.
>
>> */
>> if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) &&
>> - pci_aer_available() &&
>> - (pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER)))
>> + ((IS_ENABLED(CONFIG_PCIE_EDR) && !host->native_dpc) ||
>> + (pci_aer_available() &&
>> + (pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER)))))
>> services |= PCIE_PORT_SERVICE_DPC;
--
Sathyanarayanan Kuppuswamy
Linux kernel developer
next prev parent reply other threads:[~2020-01-17 23:06 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-12 22:43 [PATCH v12 0/8] Add Error Disconnect Recover (EDR) support sathyanarayanan.kuppuswamy
2020-01-12 22:43 ` [PATCH v12 1/8] PCI/ERR: Update error status after reset_link() sathyanarayanan.kuppuswamy
2020-01-12 22:43 ` [PATCH v12 2/8] PCI/DPC: Allow dpc_probe() even if firmware first mode is enabled sathyanarayanan.kuppuswamy
2020-01-12 22:43 ` [PATCH v12 3/8] PCI/DPC: Add dpc_process_error() wrapper function sathyanarayanan.kuppuswamy
2020-01-12 22:43 ` [PATCH v12 4/8] PCI/DPC: Add Error Disconnect Recover (EDR) support sathyanarayanan.kuppuswamy
2020-01-17 22:56 ` Bjorn Helgaas
2020-01-12 22:43 ` [PATCH v12 5/8] PCI/AER: Allow clearing Error Status Register in FF mode sathyanarayanan.kuppuswamy
2020-01-17 22:56 ` Bjorn Helgaas
2020-01-12 22:44 ` [PATCH v12 6/8] PCI/DPC: Update comments related to DPC recovery on NON_FATAL errors sathyanarayanan.kuppuswamy
2020-01-12 22:44 ` [PATCH v12 7/8] PCI/DPC: Clear AER registers in EDR mode sathyanarayanan.kuppuswamy
2020-01-12 22:44 ` [PATCH v12 8/8] PCI/ACPI: Enable EDR support sathyanarayanan.kuppuswamy
2020-01-16 22:10 ` Bjorn Helgaas
2020-01-16 22:24 ` Kuppuswamy Sathyanarayanan
2020-01-16 22:58 ` Bjorn Helgaas
2020-01-16 23:01 ` Kuppuswamy Sathyanarayanan
2020-01-17 20:41 ` Bjorn Helgaas
2020-01-17 23:04 ` Kuppuswamy Sathyanarayanan [this message]
2020-01-14 19:48 ` [PATCH v12 0/8] Add Error Disconnect Recover (EDR) support Bjorn Helgaas
2020-01-18 0:18 ` Bjorn Helgaas
2020-01-18 1:10 ` Kuppuswamy Sathyanarayanan
2020-01-18 15:15 ` Bjorn Helgaas
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