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Subject: Re: [PATCH v2 3/5] PCI: iproc: Disable MSI parsing in certain PAXC
 blocks
To:     poza@codeaurora.org
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Bjorn Helgaas <helgaas@kernel.org>,
        linux-kernel@vger.kernel.org,
        bcm-kernel-feedback-list@broadcom.com, linux-pci@vger.kernel.org,
        linux-pci-owner@vger.kernel.org
References: <1528762867-16823-1-git-send-email-ray.jui@broadcom.com>
 <1528762867-16823-4-git-send-email-ray.jui@broadcom.com>
 <8f6d7771baec3f56e0ccf5efd0efe2a2@codeaurora.org>
From:   Ray Jui <ray.jui@broadcom.com>
Message-ID: <c44bf00c-b412-2cd1-75ee-7541bc775173@broadcom.com>
Date:   Tue, 12 Jun 2018 09:58:49 -0700
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On 6/12/2018 1:29 AM, poza@codeaurora.org wrote:
> On 2018-06-12 05:51, Ray Jui wrote:
>> The internal MSI parsing logic in certain revisions of PAXC root
>> complexes does not work properly and can casue corruptions on the
>> writes. They need to be disabled
>>
>> Signed-off-by: Ray Jui <ray.jui@broadcom.com>
>> Reviewed-by: Scott Branden <scott.branden@broadcom.com>
>> ---
>>  drivers/pci/host/pcie-iproc.c | 34 ++++++++++++++++++++++++++++++++--
>>  1 file changed, 32 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/host/pcie-iproc.c 
>> b/drivers/pci/host/pcie-iproc.c
>> index 680f6b1..0804aa2 100644
>> --- a/drivers/pci/host/pcie-iproc.c
>> +++ b/drivers/pci/host/pcie-iproc.c
>> @@ -1197,10 +1197,22 @@ static int iproc_pcie_paxb_v2_msi_steer(struct
>> iproc_pcie *pcie, u64 msi_addr)
>>      return ret;
>>  }
>>
>> -static void iproc_pcie_paxc_v2_msi_steer(struct iproc_pcie *pcie, u64 
>> msi_addr)
>> +static void iproc_pcie_paxc_v2_msi_steer(struct iproc_pcie *pcie, u64 
>> msi_addr,
>> +                     bool enable)
>>  {
>>      u32 val;
>>
>> +    if (!enable) {
>> +        /*
>> +         * Disable PAXC MSI steering. All write transfers will be
>> +         * treated as non-MSI transfers
>> +         */
>> +        val = iproc_pcie_read_reg(pcie, IPROC_PCIE_MSI_EN_CFG);
>> +        val &= ~MSI_ENABLE_CFG;
>> +        iproc_pcie_write_reg(pcie, IPROC_PCIE_MSI_EN_CFG, val);
>> +        return;
> can be dropped.


No it cannot be dropped. Please review the code carefully.