linux-kernel - [PATCH] Revert "PCI/LINK: Report degraded links via link bandwidth

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Message-Id: <20190429185611.121751-1-helgaas@kernel.org>
Date:   Mon, 29 Apr 2019 13:56:10 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Alexandru Gagniuc <mr.nuke.me@...il.com>,
        Lukas Wunner <lukas@...ner.de>,
        Alex Williamson <alex.williamson@...hat.com>,
        Austin Bolen <austin_bolen@...l.com>,
        Alexandru Gagniuc <alex_gagniuc@...lteam.com>,
        Keith Busch <keith.busch@...el.com>,
        Shyam Iyer <Shyam_Iyer@...l.com>,
        Sinan Kaya <okaya@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] Revert "PCI/LINK: Report degraded links via link bandwidth

Alex W. reported a case where the new link bandwidth notification logging,
e.g.:

  vfio-pci 0000:07:00.0: 32.000 Gb/s available PCIe bandwidth, limited by 2.5 GT/s x16 link at 0000:00:02.0 (capable of 64.000 Gb/s with 5 GT/s x16 link)

is somewhat surprising.  The message is great if link bandwidth was reduced
because of a hardware problem, but in this case it's caused by a GPU doing
link state management to conserve power, so the message is to be expected
and is likely to confuse the user.

We haven't figured out a good way to handle both the "hardware failure" and
the "active link management" cases yet, so revert this for now.

Bjorn