linux-kernel - Re: [PATCH v2 0/3] PCI/DPC: Clean up DPC vs AER/EDR ownership and Kconfig

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Date: Tue, 27 Feb 2024 15:12:31 +0800
From: Ethan Zhao <haifeng.zhao@...ux.intel.com>
To: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>,
 Bjorn Helgaas <helgaas@...nel.org>, linux-pci@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Matthew W Carlis <mattc@...estorage.com>,
 Keith Busch <kbusch@...nel.org>, Lukas Wunner <lukas@...ner.de>,
 Mika Westerberg <mika.westerberg@...ux.intel.com>,
 Jesse Brandeburg <jesse.brandeburg@...el.com>,
 Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v2 0/3] PCI/DPC: Clean up DPC vs AER/EDR ownership and
 Kconfig

On 2/27/2024 2:35 PM, Kuppuswamy Sathyanarayanan wrote:
> Hi,
>
> On 2/26/24 10:18 PM, Ethan Zhao wrote:
>> On 2/23/2024 6:15 AM, Bjorn Helgaas wrote:
>>> From: Bjorn Helgaas <bhelgaas@...gle.com>
>>>
>>> Previously we could request control of DPC without AER, which is illegal
>>> per spec.  Also, we could enable CONFIG_PCIE_DPC without CONFIG_PCIE_EDR,
>>> which is also illegal.  This series addresses both.
>> I have a question here, how to understand the relationship EDR & AER ?
>> somewhere EDR touches AER status without checking _OSC granted bits,
>> such as
>>     pci_aer_raw_clear_status(edev);
>
> Which_OSC bits?
>
> EDR code will only get triggered if OS advertises the EDR support (which
> also means OS supports AER and DPC), and both AER and DPC is owned by
> the firmware. During the EDR notification, the OS is allowed to touch AER

Means no need to check if host->native_aer ? why checked in
pcie_do_recovery() ?

Thanks,
Ethan

> and DPC registers. So there is no problem with EDR code using AER routines.
>
>
>> sometimes EDR calling AER with host->native_aer checked, like
>>
>> pcie_do_recovery()
>> {
>>   ...
>>   if (host->native_aer || pcie_ports_native) {
>>          pcie_clear_device_status(dev);
>>          pci_aer_clear_nonfatal_status(dev);
>>      }
>>   ...
>> }
>>
>> That is really confusing. could we do some cleanup to eliminate it ?
>> such as seperate AER code into common code and runtime part.
>>
>>
>> Thanks,
>> Ethan
>>   
>>
>>> Bjorn Helgaas (3):
>>>     PCI/DPC: Request DPC only if also requesting AER
>>>     PCI/DPC: Remove CONFIG_PCIE_EDR
>>>     PCI/DPC: Encapsulate pci_acpi_add_edr_notifier()
>>>
>>>    drivers/acpi/pci_root.c   | 22 ++++++++++++----------
>>>    drivers/pci/pci.h         |  4 ++++
>>>    drivers/pci/pcie/Kconfig  | 14 ++++----------
>>>    drivers/pci/pcie/Makefile |  5 ++++-
>>>    drivers/pci/pcie/dpc.c    | 10 ----------
>>>    include/linux/pci-acpi.h  |  8 --------
>>>    6 files changed, 24 insertions(+), 39 deletions(-)
>>>