linux-kernel - Re: [PATCH v13 6/6] PCI/DPC: Do not do recovery for hotplug enabled system

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Message-ID: <c236b732-ed65-9f94-7ae5-b1203dff2eb0@codeaurora.org>
Date:   Mon, 16 Apr 2018 10:46:04 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Keith Busch <keith.busch@...el.com>,
        Oza Pawandeep <poza@...eaurora.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dongdong Liu <liudongdong3@...wei.com>,
        Wei Zhang <wzhang@...com>, Timur Tabi <timur@...eaurora.org>,
        Alex Williamson <alex.williamson@...hat.com>
Subject: Re: [PATCH v13 6/6] PCI/DPC: Do not do recovery for hotplug enabled
 system

On 4/15/2018 11:17 PM, Bjorn Helgaas wrote:
> It doesn't seem right to me that we handle both ERR_NONFATAL and
> ERR_FATAL events differently if we happen to have DPC support in a
> switch.
> 
> Maybe we should consider triggering DPC only on ERR_FATAL?  That would
> keep DPC out of the ERR_NONFATAL cases.
> 
>From reliability perspective, it makes sense. DPC handles NONFATAL errors
by bringing down the link. If error happened behind a switch and root port
is handling DPC, we are impacting a lot of devices operation because of one
faulty device.

Keith, do you have any preference on this direction?

> For ERR_FATAL, maybe we should bite the bullet and use
> remove/re-enumerate for AER as well as for DPC.  That would be painful
> for higher-level software, but if we're willing to accept that pain
> for new systems that support DPC, maybe life would be better overall
> if it worked the same way on systems without DPC?

Sure, we can go to this route as well.

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.