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Date:   Tue, 10 Apr 2018 14:50:08 -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
Message-ID: <20180410195008.GE54986@bhelgaas-glaptop.roam.corp.google.com>
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 <20180410194144.GD54986@bhelgaas-glaptop.roam.corp.google.com>
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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.

> > ---
> >  drivers/pci/quirks.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> > index 8b14bd3..f012742 100644
> > --- a/drivers/pci/quirks.c
> > +++ b/drivers/pci/quirks.c
> > @@ -4813,9 +4813,13 @@ static void quirk_no_ext_tags(struct pci_dev *pdev)
> >  
> >  	pci_walk_bus(bridge->bus, pci_configure_extended_tags, NULL);
> >  }
> > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0132, quirk_no_ext_tags);
> >  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0140, quirk_no_ext_tags);
> > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0141, quirk_no_ext_tags);
> >  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0142, quirk_no_ext_tags);
> >  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0144, quirk_no_ext_tags);
> > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0420, quirk_no_ext_tags);
> > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0422, quirk_no_ext_tags);
> >  
> >  #ifdef CONFIG_PCI_ATS
> >  /*
> > -- 
> > 2.7.4
> > 
> > 
> > _______________________________________________
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> > linux-arm-kernel@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel