Revert "PCI: dwc: Wait for link up only if link is started"

This reverts commit da56a1bf.

Bjorn Andersson, Fabio Estevam, Xiaolei Wang, and Jon Hunter reported that
da56a1bf ("PCI: dwc: Wait for link up only if link is started") broke
controller probing by returning an error in case the link does not come up
during host initialisation, for example when the slot is empty.

As explained in commit 886a9c13 ("PCI: dwc: Move link handling into
common code") and as indicated by the comment "Ignore errors, the link may
come up later" in the code, waiting for link up and ignoring errors is the
intended behaviour:

  Let's standardize this to succeed as there are usecases where devices
  (and the link) appear later even without hotplug. For example, a
  reconfigured FPGA device.

Reverting the offending commit specifically fixes a regression on Qualcomm
platforms like the Lenovo ThinkPad X13s which no longer reach the
interconnect sync state if a slot does not have a device populated (e.g. an
optional modem).

Note that enabling asynchronous probing by default as was done for Qualcomm
platforms by commit c0e1eb44 ("PCI: qcom: Enable async probe by
default"), should take care of any related boot time concerns.

Finally, note that the intel-gw driver is the only driver currently not
providing a .start_link() callback and instead starts the link in its
.host_init() callback, which may avoid an additional one-second timeout
during probe by making the link-up wait conditional. If anyone cares, that
can be done in a follow-up patch with a proper motivation.

[bhelgaas: add Fabio Estevam, Xiaolei Wang, Jon Hunter reports]
Fixes: da56a1bf ("PCI: dwc: Wait for link up only if link is started")
Link: https://lore.kernel.org/r/20230706082610.26584-1-johan+linaro@kernel.org


Reported-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reported-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20230704122635.1362156-1-festevam@gmail.com/


Reported-by: Xiaolei Wang <xiaolei.wang@windriver.com>
Link: https://lore.kernel.org/r/20230705010624.3912934-1-xiaolei.wang@windriver.com/


Reported-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://lore.kernel.org/r/6ca287a1-6c7c-7b90-9022-9e73fb82b564@nvidia.com


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Sajid Dalvi <sdalvi@google.com>
Cc: Ajay Agarwal <ajayagarwal@google.com>