linux-kernel - Re: [PATCH 2/2] pci: Don't set RCB bit in LNKCTL if the upstream bridge hasn't

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Message-ID: <20161115125822.sna3oz56prmrelgc@linux-x5ow.site>
Date:   Tue, 15 Nov 2016 13:58:22 +0100
From:   Johannes Thumshirn <jthumshirn@...e.de>
To:     Don Dutile <ddutile@...hat.com>
Cc:     Bjorn Helgaas <helgaas@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, Alexander Graf <agraf@...e.de>,
        Hannes Reinecke <hare@...e.de>
Subject: Re: [PATCH 2/2] pci: Don't set RCB bit in LNKCTL if the upstream
 bridge hasn't

On Mon, Nov 14, 2016 at 11:16:51AM -0500, Don Dutile wrote:
> On 11/14/2016 06:56 AM, Johannes Thumshirn wrote:
> > On Wed, Nov 09, 2016 at 11:11:40AM -0600, Bjorn Helgaas wrote:
> > > Hi Johannes,
> > > 
> > > On Wed, Nov 02, 2016 at 04:35:52PM -0600, Johannes Thumshirn wrote:
> > > > The Read Completion Boundary (RCB) bit must only be set on a device or
> > > > endpoint if it is set on the root complex.
> > > > 
> > > > Certain BIOSes erroneously set the RCB Bit in their ACPI _HPX Tables
> > > > even if it is not set on the root port. This is a violation to the PCIe
> > > > Specification and is known to bring some Mellanox Connect-X 3 HCAs into
> > > > a state where they can't map their firmware and go into error recovery.
> > > > 
> > > > BIOS Information
> > > > 	Vendor: IBM
> > > > 	Version: -[A8E120CUS-1.30]-
> > > > 	Release Date: 08/22/2016
> > > 
> > > This seems like a pretty serious problem (sounds like maybe the HCA is
> > > completely useless?)
> > 
> > Correct.
> > 
> > > 
> > > Can you point us at a bugzilla or other problem report?  It's nice to
> > > have details of what this looks like to a user, so people who trip
> > > over this problem have a little more chance of finding the solution.
> > 
> > As we already said, our bugzilla entry for this is not accessible from the
> > outside, but I know Red Hat does have a bugzilla entry for the same issue as
> > well. Maybe this is reachable from the outside (adding Don for this, as I know
> > he has worked on this problem as well).
> > 
> RHEL bz's are not accessible from the outside.
> I suggest capturing the content of the RH bz issue and creating a k.o. bz
> with the information.

I've created https://bugzilla.kernel.org/show_bug.cgi?id=187781 to track this
on b.k.o. Feel free to add any information you have.

@Bjorn anything else I can provide in order to get the fix applied?

Byte,
 	Johannes

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Johannes Thumshirn                                          Storage
jthumshirn@...e.de                                +49 911 74053 689
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