linux-kernel - Re: [PATCH] PCI: Mark Haswell Power Control Unit as having non-compliant BARs

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Message-ID: <57C7100D.3010407@redhat.com>
Date:   Wed, 31 Aug 2016 13:12:45 -0400
From:   Prarit Bhargava <prarit@...hat.com>
To:     Myron Stowe <myron.stowe@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
CC:     linux-pci <linux-pci@...r.kernel.org>,
        Paul Menzel <pmenzel@...gen.mpg.de>,
        Andi Kleen <ak@...ux.intel.com>,
        Myron Stowe <myron.stowe@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PCI: Mark Haswell Power Control Unit as having non-compliant
 BARs

On 08/31/2016 12:46 PM, Myron Stowe wrote:
> On Wed, Aug 31, 2016 at 9:50 AM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
>> The Haswell Power Control Unit has a non-PCI register (CONFIG_TDP_NOMINAL)
>> where BAR 0 is supposed to be.  This is erratum HSE43 in the spec update
>> referenced below:
>>
>>   The PCIe* Base Specification indicates that Configuration Space Headers
>>   have a base address register at offset 0x10.  Due to this erratum, the
>>   Power Control Unit's CONFIG_TDP_NOMINAL CSR (Bus 1; Device 30; Function
>>   3; Offset 0x10) is located where a base register is expected.
>>
>> Mark the PCU as having non-compliant BARs so we don't try to probe any of
>> them.  There are no other BARs on this device.
>>
>> Rename the quirk so it's not Broadwell-specific.
> 
> While it's not a big enough battle to fight it sure is irritating to
> see vendors make the same mistakes over and over again.  Wondering if
> this an error on the respective vendor's BIOS team's part or is this
> is just being inherited over and over again from Intel's Premier BIOS
> team reference code?
> 

This isn't a BIOS issue.  The actual hardware is manufactured this
way, and the documentation indicates that the hardware has
non-compliant BARs.

Testing and reviewing now ...

P.



>>
>> Link: http://www.intel.com/content/www/us/en/processors/xeon/xeon-e5-v3-spec-update.html
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=153881
>> Reported-by: Paul Menzel <pmenzel@...gen.mpg.de>
>> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
>> ---
>>  arch/x86/pci/fixup.c |   20 +++++++++++++-------
>>  1 file changed, 13 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
>> index 837ea36..6d52b94 100644
>> --- a/arch/x86/pci/fixup.c
>> +++ b/arch/x86/pci/fixup.c
>> @@ -553,15 +553,21 @@ static void twinhead_reserve_killing_zone(struct pci_dev *dev)
>>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x27B9, twinhead_reserve_killing_zone);
>>
>>  /*
>> - * Broadwell EP Home Agent BARs erroneously return non-zero values when read.
>> + * Device [8086:2fc0]
>> + * Erratum HSE43
>> + * CONFIG_TDP_NOMINAL CSR Implemented at Incorrect Offset
>> + * http://www.intel.com/content/www/us/en/processors/xeon/xeon-e5-v3-spec-update.html
>>   *
>> - * See http://www.intel.com/content/www/us/en/processors/xeon/xeon-e5-v4-spec-update.html
>> - * entry BDF2.
>> + * Devices [8086:6f60,6fa0,6fc0]
>> + * Erratum BDF2
>> + * PCI BARs in the Home Agent Will Return Non-Zero Values During Enumeration
>> + * http://www.intel.com/content/www/us/en/processors/xeon/xeon-e5-v4-spec-update.html
>>   */
>> -static void pci_bdwep_bar(struct pci_dev *dev)
>> +static void pci_invalid_bar(struct pci_dev *dev)
>>  {
>>         dev->non_compliant_bars = 1;
>>  }
>> -DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6f60, pci_bdwep_bar);
>> -DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6fa0, pci_bdwep_bar);
>> -DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6fc0, pci_bdwep_bar);
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2fc0, pci_invalid_bar);
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6f60, pci_invalid_bar);
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6fa0, pci_invalid_bar);
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6fc0, pci_invalid_bar);
>>
> 
> Acked-by: Myron Stowe <myron.stowe@...hat.com>
> 
>