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

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Message-ID: <CAHp75VdmHvfXvLDUpyVb9QiWCG0YSPErQ+O=Lvdj2NS6WrcdZQ@mail.gmail.com>
Date:   Tue, 5 Jun 2018 16:04:19 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Alexandru Gagniuc <mr.nuke.me@...il.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>, alex_gagniuc@...lteam.com,
        austin_bolen@...l.com, shyam_iyer@...l.com,
        Keith Busch <keith.busch@...el.com>, linux-pci@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] PCI: Check for PCIe downtraining conditions

On Tue, Jun 5, 2018 at 3:27 PM, Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
> On Mon, Jun 4, 2018 at 6:55 PM, Alexandru Gagniuc <mr.nuke.me@...il.com> wrote:
>> PCIe downtraining happens when both the device and PCIe port are
>> capable of a larger bus width or higher speed than negotiated.
>> Downtraining might be indicative of other problems in the system, and
>> identifying this from userspace is neither intuitive, nor straigh
>> forward.
>>
>> The easiest way to detect this is with pcie_print_link_status(),
>> since the bottleneck is usually the link that is downtrained. It's not
>> a perfect solution, but it works extremely well in most cases.
>
> Have you seen any of my comments?
> For your convenience repeating below.

Ah, found the answer in a pile of emails. OK, I see your point about
helper, though the rest is still applicable here.

-- 
With Best Regards,
Andy Shevchenko