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Date:   Wed, 11 Apr 2018 08:51:51 -0500
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Sinan Kaya <okaya@codeaurora.org>
Cc:     linux-pci@vger.kernel.org, sulrich@codeaurora.org,
        timur@codeaurora.org, linux-arm-msm@vger.kernel.org,
        Bjorn Helgaas <bhelgaas@google.com>,
        open list <linux-kernel@vger.kernel.org>,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] PCI: quirk HT1100 & HT2000 and one HT2100 Root Ports for
 Extended Tags
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On Tue, Apr 10, 2018 at 04:18:01PM -0400, Sinan Kaya wrote:
> On 4/10/2018 3:50 PM, Bjorn Helgaas wrote:
> > On Tue, Apr 10, 2018 at 02:41:44PM -0500, Bjorn Helgaas wrote:
> >> On Wed, Apr 04, 2018 at 06:50:09PM -0400, Sinan Kaya wrote:
> >>> Per PCIe r3.1, sec 2.2.6.2 and 7.8.4, a Requester may not use 8-bit Tags
> >>> unless its Extended Tag Field Enable is set, but all Receivers/Completers
> >>> must handle 8-bit Tags correctly regardless of their Extended Tag Field
> >>> Enable.
> >>>
> >>> Some devices do not handle 8-bit Tags as Completers, so add a quirk for
> >>> them.  If we find such a device, we disable Extended Tags for the entire
> >>> hierarchy to make peer-to-peer DMA possible.
> >>>
> >>> The Broadcom HT1100/HT2000/HT2100 seems to have issues with handling 8-bit
> >>> tags.  Mark it as broken.
> >>>
> >>> Fixes: 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported")
> >>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=196197
> >>> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> >> Applied to pci/enumeration for v4.18, thanks!
> > Actually, this is a really annoying issue and I think the fix is
> > appropriate for v4.17, so I moved it to my for-linus branch.
> > 
> 
> I agree. It causes boot issues on some AMD Opteron machines. It should
> probably be back-ported too. 

We started enabling extended tags with 60db3a4d8cc9 ("PCI: Enable PCIe
Extended Tags if supported"), which appeared in v4.11.

So I added these stable tags:

  CC: stable@vger.kernel.org      # v4.11: 62ce94a7a5a5 PCI: Mark Broadcom HT2100 Root Port Extended Tags as broken
  CC: stable@vger.kernel.org      # v4.11

I'm not sure I'm using the stable request correctly, but my intent is:

  - 62ce94a7a5a5 appeared in v4.14, so cherry-pick 62ce94a7a5a5 to
    v4.11 through v4.13
  - cherry-pick *this* patch on top of 62ce94a7a5a5 to v4.11 and later