mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-06 07:34:03 -04:00
8037ac08c2
The LBMS bit, where implemented, is set by hardware either in response
to the completion of retraining caused by writing 1 to the Retrain Link
bit or whenever hardware has changed the link speed or width in attempt
to correct unreliable link operation. It is never cleared by hardware
other than by software writing 1 to the bit position in the Link Status
register and we never do such a write.
We currently have two places, namely apply_bad_link_workaround() and
pcie_failed_link_retrain() in drivers/pci/controller/dwc/pcie-tegra194.c
and drivers/pci/quirks.c respectively where we check the state of the LBMS
bit and neither is interested in the state of the bit resulting from the
completion of retraining, both check for a link fault.
And in particular pcie_failed_link_retrain() causes issues consequently, by
trying to retrain a link where there's no downstream device anymore and the
state of 1 in the LBMS bit has been retained from when there was a device
downstream that has since been removed.
Clear the LBMS bit then at the conclusion of pcie_retrain_link(), so that
we have a single place that controls it and that our code can track link
speed or width changes resulting from unreliable link operation.
Fixes: a89c82249c ("PCI: Work around PCIe link training failures")
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2408091133140.61955@angie.orcam.me.uk
Reported-by: Matthew W Carlis <mattc@purestorage.com>
Link: https://lore.kernel.org/r/20240806000659.30859-1-mattc@purestorage.com/
Link: https://lore.kernel.org/r/20240722193407.23255-1-mattc@purestorage.com/
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Cc: <stable@vger.kernel.org> # v6.5+
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.