PCI: Unify delay handling for reset and resume

PCI: Unify delay handling for reset and resume

commit ac91e6980563ed53afadd925fa6585ffd2bc4a2c upstream.

Sheng Bi reports that pci_bridge_secondary_bus_reset() may fail to wait
for devices on the secondary bus to become accessible after reset:

Although it does call pci_dev_wait(), it erroneously passes the bridge's
pci_dev rather than that of a child.  The bridge of course is always
accessible while its secondary bus is reset, so pci_dev_wait() returns
immediately.

Sheng Bi proposes introducing a new pci_bridge_secondary_bus_wait()
function which is called from pci_bridge_secondary_bus_reset():

https://lore.kernel.org/linux-pci/20220523171517.32407-1-windy.bi.enflame@gmail.com/

However we already have pci_bridge_wait_for_secondary_bus() which does
almost exactly what we need.  So far it's only called on resume from
D3cold (which implies a Fundamental Reset per PCIe r6.0 sec 5.8).
Re-using it for Secondary Bus Resets is a leaner and more rational
approach than introducing a new function.

That only requires a few minor tweaks:

- Amend pci_bridge_wait_for_secondary_bus() to await accessibility of
  the first device on the secondary bus by calling pci_dev_wait() after
  performing the prescribed delays.  pci_dev_wait() needs two parameters,
  a reset reason and a timeout, which callers must now pass to
  pci_bridge_wait_for_secondary_bus().  The timeout is 1 sec for resume
  (PCIe r6.0 sec 6.6.1) and 60 sec for reset (commit ed04eeb36f99 ("PCI:
  Wait up to 60 seconds for device to become ready after FLR")).
  Introduce a PCI_RESET_WAIT macro for the 1 sec timeout.

- Amend pci_bridge_wait_for_secondary_bus() to return 0 on success or
  -ENOTTY on error for consumption by pci_bridge_secondary_bus_reset().

- Drop an unnecessary 1 sec delay from pci_reset_secondary_bus() which
  is now performed by pci_bridge_wait_for_secondary_bus().  A static
  delay this long is only necessary for Conventional PCI, so modern
  PCIe systems benefit from shorter reset times as a side effect.

Fixes: c24dd8571896 ("PCI: Wait for device to become ready after secondary bus reset")
Link: https://lore.kernel.org/r/da77c92796b99ec568bd070cbe4725074a117038.1673769517.git.lukas@wunner.de
Reported-by: Sheng Bi <windy.bi.enflame@gmail.com>
Tested-by: Ravi Kishore Koppuravuri <ravi.kishore.koppuravuri@intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: stable@vger.kernel.org # v4.17+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>