linux-kernel - Re: [PATCH] PCI: layerscape: Change back to the default error response behavior

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Date:   Wed, 30 Sep 2020 21:12:07 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Rob Herring <robh@...nel.org>
CC:     Zhiqiang Hou <Zhiqiang.Hou@....com>,
        PCI <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Minghuan Lian <minghuan.Lian@....com>,
        Roy Zang <roy.zang@....com>, Mingkai Hu <mingkai.hu@....com>,
        Yang-Leo Li <leoyang.li@....com>
Subject: Re: [PATCH] PCI: layerscape: Change back to the default error
 response behavior

Hi,

On 30/09/20 8:37 pm, Rob Herring wrote:
> On Wed, Sep 30, 2020 at 8:29 AM Kishon Vijay Abraham I <kishon@...com> wrote:
>>
>> Hi Hou,
>>
>> On 29/09/20 6:43 pm, Zhiqiang Hou wrote:
>>> From: Hou Zhiqiang <Zhiqiang.Hou@....com>
>>>
>>> In the current error response behavior, it will send a SLVERR response
>>> to device's internal AXI slave system interface when the PCIe controller
>>> experiences an erroneous completion (UR, CA and CT) from an external
>>> completer for its outbound non-posted request, which will result in
>>> SError and crash the kernel directly.
>>> This patch change back it to the default behavior to increase the
>>> robustness of the kernel. In the default behavior, it always sends an
>>> OKAY response to the internal AXI slave interface when the controller
>>> gets these erroneous completions. And the AER driver will report and
>>> try to recover these errors.
>>
>> I don't think not forwarding any error interrupts is a good idea.
> 
> Interrupts would be fine. Abort/SError is not. I think it is pretty
> clear what the correct behavior is for config accesses.

IIUC $patch prevents SError in all cases. Doesn't UR, CA and CT all
sends SLVERR which will result in Abort and that is being prevented
here?. Maybe I'm wrong here, Hou can confirm.

Thanks
Kishon