tree 151d8d0bddeff3de649bfd4cb7037904f6f59668
parent 237b5a362399bdd81422ef9f9ac9b9f034161efd
author Sinan Kaya <okaya@codeaurora.org> 1504035945 -0500
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1524994318 +0200

PCI: Wait up to 60 seconds for device to become ready after FLR

commit 821cdad5c46cae94ce65b9a98614c70a6ff021f8 upstream.

Sporadic reset issues have been observed with an Intel 750 NVMe drive while
assigning the physical function to the guest machine.  The sequence of
events observed is as follows:

  - perform a Function Level Reset (FLR)
  - sleep up to 1000ms total
  - read ~0 from PCI_COMMAND (CRS completion for config read)
  - warn that the device didn't return from FLR
  - touch the device before it's ready
  - device drops config writes when we restore register settings (there's
    no mechanism for software to learn about CRS completions for writes)
  - incomplete register restore leaves device in inconsistent state
  - device probe fails because device is in inconsistent state

After reset, an endpoint may respond to config requests with Configuration
Request Retry Status (CRS) to indicate that it is not ready to accept new
requests. See PCIe r3.1, sec 2.3.1 and 6.6.2.

Increase the timeout value from 1 second to 60 seconds to cover the period
where device responds with CRS and also report polling progress.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
[bhelgaas: include the mandatory 100ms in the delays we print]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>