linux-kernel - Re: [PATCH v3] PCI: Check for PCIe downtraining conditions

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Message-ID: <d7da53d3-1631-7d3f-5b78-15a8af30a759@mellanox.com>
Date:   Tue, 24 Jul 2018 00:35:39 +0300
From:   Tal Gilboa <talgi@...lanox.com>
To:     "Alex G." <mr.nuke.me@...il.com>,
        Bjorn Helgaas <helgaas@...nel.org>
Cc:     bhelgaas@...gle.com, alex_gagniuc@...lteam.com,
        austin_bolen@...l.com, shyam_iyer@...l.com, keith.busch@...el.com,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Ariel Elior <ariel.elior@...ium.com>,
        Michael Chan <michael.chan@...adcom.com>,
        Ganesh Goudar <ganeshgr@...lsio.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Dave Airlie <airlied@...il.com>,
        Alex Deucher <alexander.deucher@....com>
Subject: Re: [PATCH v3] PCI: Check for PCIe downtraining conditions

On 7/23/2018 8:01 PM, Alex G. wrote:
> On 07/23/2018 12:21 AM, Tal Gilboa wrote:
>> On 7/19/2018 6:49 PM, Alex G. wrote:
>>>
>>>
>>> On 07/18/2018 08:38 AM, Tal Gilboa wrote:
>>>> On 7/16/2018 5:17 PM, Bjorn Helgaas wrote:
>>>>> [+cc maintainers of drivers that already use pcie_print_link_status()
>>>>> and GPU folks]
>>> [snip]
>>>>>
>>>>>> +    /* Multi-function PCIe share the same link/status. */
>>>>>> +    if ((PCI_FUNC(dev->devfn) != 0) || dev->is_virtfn)
>>>>>> +        return;
>>>>>> +
>>>>>> +    pcie_print_link_status(dev);
>>>>>> +}
>>>>
>>>> Is this function called by default for every PCIe device? What about 
>>>> VFs? We make an exception for them on our driver since a VF doesn't 
>>>> have access to the needed information in order to provide a 
>>>> meaningful message.
>>>
>>> I'm assuming VF means virtual function. pcie_print_link_status() 
>>> doesn't care if it's passed a virtual function. It will try to do its 
>>> job. That's why I bail out three lines above, with 'dev->is_virtfn' 
>>> check.
>>>
>>> Alex
>>
>> That's the point - we don't want to call pcie_print_link_status() for 
>> virtual functions. We make the distinction in our driver. If you want 
>> to change the code to call this function by default it shouldn't 
>> affect the current usage.
> 
> I'm not understanding very well what you're asking. I understand you 
> want to avoid printing this message on virtual functions, and that's 
> already taken care of. I'm also not changing current behavior.  Let's 
> get v2 out and start the discussion again based on that.
> 
> Alex

Oh ok I see. In this case, please remove the explicit call in mlx4/5 
drivers so it won't be duplicated.