• Sinan Kaya's avatar
    PCI: Wait up to 60 seconds for device to become ready after FLR · c8b1584e
    Sinan Kaya authored
    commit 821cdad5 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: default avatarSinan Kaya <okaya@codeaurora.org>
    [bhelgaas: include the mandatory 100ms in the delays we print]
    Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    c8b1584e
pci.c 138 KB