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[Manoj Iyer <1788850@xxxxxxxxxxxxxxxxxx>]

*** This bug is a duplicate of bug 1805245 ***
    https://bugs.launchpad.net/bugs/1805245

** This bug is no longer a duplicate of bug 1788549
   powerpc/powernv/pci: Work around races in PCI bridge enabling
** This bug has been marked a duplicate of bug 1805245
   powerpc/powernv/pci: Work around races in PCI bridge enabling

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https://bugs.launchpad.net/bugs/1788850

Title:
  [Bionic, Xenial] powerpc/powernv/pci: Work around races in PCI bridge
  enabling

Status in The Ubuntu-power-systems project:
  New
Status in linux package in Ubuntu:
  Triaged
Status in linux source package in Xenial:
  Triaged
Status in linux source package in Bionic:
  Triaged

Bug description:
  == Comment: #0 - Breno Leitao <brenohl@xxxxxxxxxx> - 2018-08-23 17:52:30 ==
  Please apply the following kernel patch into Bionic  4.15 kernel, and Xenial 4.4 kernel.

  https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=next&id=db2173198b9513f7add8009f225afa1f1c79bcc6

  powerpc/powernv/pci: Work around races in PCI bridge enabling

  The generic code is racy when multiple children of a PCI bridge try to
  enable it simultaneously.

  This leads to drivers trying to access a device through a
  not-yet-enabled bridge, and this EEH errors under various
  circumstances when using parallel driver probing.

  There is work going on to fix that properly in the PCI core but it
  will take some time.

  x86 gets away with it because (outside of hotplug), the BIOS enables
  all the bridges at boot time.

  This patch does the same thing on powernv by enabling all bridges that
  have child devices at boot time, thus avoiding subsequent races. It's
  suitable for backporting to stable and distros, while the proper PCI
  fix will probably be significantly more invasive.

  Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
  Cc: stable@xxxxxxxxxxxxxxx
  Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>

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