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From: "Kuppuswamy, Sathyanarayanan"  <sathyanarayanan.kuppuswamy@linux.intel.com>
To: Bjorn Helgaas <helgaas@kernel.org>,
	Yicong Yang <yangyicong@hisilicon.com>
Cc: linux-pci@vger.kernel.org, kbusch@kernel.org,
	sean.v.kelley@intel.com, qiuxu.zhuo@intel.com,
	prime.zeng@huawei.com, linuxarm@openeuler.org
Subject: Re: [PATCH] PCI/DPC: Disable ERR_COR explicitly for native dpc service
Date: Sun, 11 Apr 2021 20:32:19 -0700	[thread overview]
Message-ID: <dcd63859-2c66-2f0b-b6ca-877e50fbcee3@linux.intel.com> (raw)
In-Reply-To: <20210410152103.GA2043340@bjorn-Precision-5520>



On 4/10/21 8:21 AM, Bjorn Helgaas wrote:
> On Wed, Feb 03, 2021 at 08:53:15PM +0800, Yicong Yang wrote:
>> Per Downstream Port Containment Related Enhancements ECN[1],
>> Table 4-6 Interpretation of _OSC Control Field Returned Value,
>> for bit 7 of _OSC control return value:
>>
>>    "If firmware allows the OS control of this feature, then,
>>    in the context of the _OSC method the OS must ensure that
>>    Downstream Port Containment ERR_COR signaling is disabled
>>    as described in the PCI Express Base Specification."
>>
>> and PCI Express Base Specification Revision 4.0 Version 1.0
>> section 6.2.10.2, Use of DPC ERR_COR Signaling:
>>
>>    "...DPC ERR_COR signaling is primarily intended for use by
>>    platform firmware..."
>>
>> Currently we don't set DPC ERR_COR enable bit, but explicitly
>> clear the bit to ensure it's disabled.
Instead of spec reference, can you explain what error you are
fixing? without this fix what will be the impact and explain
how you mitigating it with your fix.
>>
>> [1] Downstream Port Containment Related Enhancements ECN,
>>      Jan 28, 2019, affecting PCI Firmware Specification, Rev. 3.2
>>      https://members.pcisig.com/wg/PCI-SIG/document/12888
>>
>> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
> 
> Anybody want to chime in and review this?  Sometimes I feel like a
> one-man band :)
> 
>> ---
>>   drivers/pci/pcie/dpc.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
>> index e05aba8..5cc8ef3 100644
>> --- a/drivers/pci/pcie/dpc.c
>> +++ b/drivers/pci/pcie/dpc.c
>> @@ -302,7 +302,7 @@ static int dpc_probe(struct pcie_device *dev)
>>   	pci_read_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CAP, &cap);
>>   	pci_read_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, &ctl);
>>   
>> -	ctl = (ctl & 0xfff4) | PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN;
>> +	ctl = (ctl & 0xffe4) | PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN;
>>   	pci_write_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, ctl);
>>   	pci_info(pdev, "enabled with IRQ %d\n", dev->irq);
>>   
>> -- 
>> 2.8.1
>>

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer

  parent reply	other threads:[~2021-04-12  3:32 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-03 12:53 [PATCH v2] PCI/DPC: Check host->native_dpc before enable dpc service Yicong Yang
2021-02-03 12:53 ` [PATCH] PCI/DPC: Disable ERR_COR explicitly for native " Yicong Yang
2021-02-18 17:20   ` Bjorn Helgaas
2021-02-24  8:56     ` Yicong Yang
2021-04-10 15:21   ` Bjorn Helgaas
2021-04-10 19:17     ` Lukas Wunner
2021-04-12  9:32       ` Yicong Yang
2021-04-12  3:32     ` Kuppuswamy, Sathyanarayanan [this message]
2021-04-12  9:46       ` Yicong Yang
2021-02-24  9:47 ` [PATCH v2] PCI/DPC: Check host->native_dpc before enable " Yicong Yang
2021-07-26 22:05   ` Bjorn Helgaas
2021-07-28  9:22     ` Yicong Yang

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