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Date: Thu, 16 Jan 2020 14:24:10 -0800
From: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
ashok.raj@...el.com, "Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <lenb@...nel.org>,
Keith Busch <keith.busch@...el.com>,
Huong Nguyen <huong.nguyen@...l.com>,
Austin Bolen <Austin.Bolen@...l.com>
Subject: Re: [PATCH v12 8/8] PCI/ACPI: Enable EDR support
On 1/16/20 2:10 PM, Bjorn Helgaas wrote:
> On Sun, Jan 12, 2020 at 02:44:02PM -0800, sathyanarayanan.kuppuswamy@...ux.intel.com wrote:
>> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.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.
>>
>> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
>> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
>> Cc: Len Brown <lenb@...nel.org>
>> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
>> Acked-by: Keith Busch <keith.busch@...el.com>
>> Tested-by: Huong Nguyen <huong.nguyen@...l.com>
>> Tested-by: Austin Bolen <Austin.Bolen@...l.com>
>> ---
>> drivers/acpi/pci_root.c | 9 +++++++++
>> drivers/pci/pcie/portdrv_core.c | 7 +++++--
>> drivers/pci/probe.c | 1 +
>> include/linux/acpi.h | 6 ++++--
>> include/linux/pci.h | 3 ++-
>> 5 files changed, 21 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> index d1e666ef3fcc..134e20474dfd 100644
>> --- a/drivers/acpi/pci_root.c
>> +++ b/drivers/acpi/pci_root.c
>> @@ -131,6 +131,7 @@ static struct pci_osc_bit_struct pci_osc_support_bit[] = {
>> { OSC_PCI_CLOCK_PM_SUPPORT, "ClockPM" },
>> { OSC_PCI_SEGMENT_GROUPS_SUPPORT, "Segments" },
>> { OSC_PCI_MSI_SUPPORT, "MSI" },
>> + { OSC_PCI_EDR_SUPPORT, "EDR" },
>> { OSC_PCI_HPX_TYPE_3_SUPPORT, "HPX-Type3" },
>> };
>>
>> @@ -141,6 +142,7 @@ static struct pci_osc_bit_struct pci_osc_control_bit[] = {
>> { OSC_PCI_EXPRESS_AER_CONTROL, "AER" },
>> { OSC_PCI_EXPRESS_CAPABILITY_CONTROL, "PCIeCapability" },
>> { OSC_PCI_EXPRESS_LTR_CONTROL, "LTR" },
>> + { OSC_PCI_EXPRESS_DPC_CONTROL, "DPC" },
>> };
>>
>> static void decode_osc_bits(struct acpi_pci_root *root, char *msg, u32 word,
>> @@ -440,6 +442,8 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
>> support |= OSC_PCI_ASPM_SUPPORT | OSC_PCI_CLOCK_PM_SUPPORT;
>> if (pci_msi_enabled())
>> support |= OSC_PCI_MSI_SUPPORT;
>> + if (IS_ENABLED(CONFIG_PCIE_EDR))
>> + support |= OSC_PCI_EDR_SUPPORT;
>>
>> decode_osc_support(root, "OS supports", support);
>> status = acpi_pci_osc_support(root, support);
>> @@ -487,6 +491,9 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
>> control |= OSC_PCI_EXPRESS_AER_CONTROL;
>> }
>>
>> + if (IS_ENABLED(CONFIG_PCIE_DPC))
>> + control |= OSC_PCI_EXPRESS_DPC_CONTROL;
> The ECN [1] says:
>
> If this bit is set by the OS, this indicates that it supports both
> native OS control and firmware ownership models (i.e. Error
> Disconnect Recover notification) of Downstream Port Containment.
>
> But if CONFIG_PCIE_DPC=y and CONFIG_PCIE_EDR is not set, we will set
> OSC_PCI_EXPRESS_DPC_CONTROL even though we don't support EDR. That
> doesn't seem to match what the spec says.
Agreed.
>
> I think this needs to be something like:
>
> if (IS_ENABLED(CONFIG_PCIE_DPC) && IS_ENABLED(CONFIG_PCIE_EDR))
> control |= OSC_PCI_EXPRESS_DPC_CONTROL;
Since CONFIG_PCIE_EDR has dependency on CONFIG_PCIE_DPC,
I think we can just use IS_ENABLED(CONFIG_PCIE_EDR) here.
I will fix it and send an update. You want to me to send a new
patch set of just an update to this patch ?
>
> [1] Downstream Port Containment related Enhancements, PCI ECN, Jan 28,
> 2019, Section 4.5.1, Table 4-5.
>
>> requested = control;
>> status = acpi_pci_osc_control_set(handle, &control,
>> OSC_PCI_EXPRESS_CAPABILITY_CONTROL);
>> @@ -916,6 +923,8 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
>> host_bridge->native_pme = 0;
>> if (!(root->osc_control_set & OSC_PCI_EXPRESS_LTR_CONTROL))
>> host_bridge->native_ltr = 0;
>> + if (!(root->osc_control_set & OSC_PCI_EXPRESS_DPC_CONTROL))
>> + host_bridge->native_dpc = 0;
>>
>> /*
>> * Evaluate the "PCI Boot Configuration" _DSM Function. If it
>> diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
>> index 5075cb9e850c..009742c865d6 100644
>> --- 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.
>> */
>> 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;
>>
>> if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM ||
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index 512cb4312ddd..c9a9c5b42e72 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -598,6 +598,7 @@ static void pci_init_host_bridge(struct pci_host_bridge *bridge)
>> bridge->native_shpc_hotplug = 1;
>> bridge->native_pme = 1;
>> bridge->native_ltr = 1;
>> + bridge->native_dpc = 1;
>> }
>>
>> struct pci_host_bridge *pci_alloc_host_bridge(size_t priv)
>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>> index 0f37a7d5fa77..0a7aaa452a98 100644
>> --- a/include/linux/acpi.h
>> +++ b/include/linux/acpi.h
>> @@ -515,8 +515,9 @@ extern bool osc_pc_lpi_support_confirmed;
>> #define OSC_PCI_CLOCK_PM_SUPPORT 0x00000004
>> #define OSC_PCI_SEGMENT_GROUPS_SUPPORT 0x00000008
>> #define OSC_PCI_MSI_SUPPORT 0x00000010
>> +#define OSC_PCI_EDR_SUPPORT 0x00000080
>> #define OSC_PCI_HPX_TYPE_3_SUPPORT 0x00000100
>> -#define OSC_PCI_SUPPORT_MASKS 0x0000011f
>> +#define OSC_PCI_SUPPORT_MASKS 0x0000019f
>>
>> /* PCI Host Bridge _OSC: Capabilities DWORD 3: Control Field */
>> #define OSC_PCI_EXPRESS_NATIVE_HP_CONTROL 0x00000001
>> @@ -525,7 +526,8 @@ extern bool osc_pc_lpi_support_confirmed;
>> #define OSC_PCI_EXPRESS_AER_CONTROL 0x00000008
>> #define OSC_PCI_EXPRESS_CAPABILITY_CONTROL 0x00000010
>> #define OSC_PCI_EXPRESS_LTR_CONTROL 0x00000020
>> -#define OSC_PCI_CONTROL_MASKS 0x0000003f
>> +#define OSC_PCI_EXPRESS_DPC_CONTROL 0x00000080
>> +#define OSC_PCI_CONTROL_MASKS 0x000000bf
>>
>> #define ACPI_GSB_ACCESS_ATTRIB_QUICK 0x00000002
>> #define ACPI_GSB_ACCESS_ATTRIB_SEND_RCV 0x00000004
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index c393dff2d66f..0b7c63c7888d 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -510,8 +510,9 @@ struct pci_host_bridge {
>> unsigned int native_shpc_hotplug:1; /* OS may use SHPC hotplug */
>> unsigned int native_pme:1; /* OS may use PCIe PME */
>> unsigned int native_ltr:1; /* OS may use PCIe LTR */
>> - unsigned int preserve_config:1; /* Preserve FW resource setup */
>> + unsigned int native_dpc:1; /* OS may use PCIe DPC */
>>
>> + unsigned int preserve_config:1; /* Preserve FW resource setup */
> The blank line should stay after the bitfields. Then this will look
> like the simple insertion of native_dpc, as it should.
>
>> /* Resource alignment requirements */
>> resource_size_t (*align_resource)(struct pci_dev *dev,
>> const struct resource *res,
>> --
>> 2.21.0
>>
--
Sathyanarayanan Kuppuswamy
Linux kernel developer
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