[PATCH v1 2/2] PCI: dwc: Wait for link up only if link is started

[Ajay Agarwal <ajayagarwal@google.com>]

In dw_pcie_host_init(), regardless of whether the link has been
started or not, the code waits for the link to come up. Even in
cases where .start_link() is not defined the code ends up
spinning in a loop for one second. Since in some systems
dw_pcie_host_init() gets called during probe, this one second
loop for each PCIe interface instance ends up extending the boot
time.

Signed-off-by: Ajay Agarwal <ajayagarwal@google.com>
---
This is actually patch v6 for [1] which I have made a part of the
patch series.

v4 [2] was applied, but then reverted [3]. The reason being v4 added
a regression on some products which expect the link to not come
up as a part of the probe. Since v4 returned error from
dw_pcie_wait_for_link check, the probe function of these products
started to fail.

[1] https://lore.kernel.org/all/20240112093006.2832105-1-ajayagarwal@google.com/
[2] https://lore.kernel.org/all/20230412093425.3659088-1-ajayagarwal@google.com/
[3] https://lore.kernel.org/all/20230706082610.26584-1-johan+linaro@kernel.org/

 drivers/pci/controller/dwc/pcie-designware-host.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 7991f0e179b2..e53132663d1d 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -487,14 +487,18 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
 	if (ret)
 		goto err_remove_edma;
 
-	if (!dw_pcie_link_up(pci)) {
+	if (dw_pcie_link_up(pci)) {
+		dw_pcie_print_link_status(pci);
+	} else {
 		ret = dw_pcie_start_link(pci);
 		if (ret)
 			goto err_remove_edma;
-	}
 
-	/* Ignore errors, the link may come up later */
-	dw_pcie_wait_for_link(pci);
+		if (pci->ops && pci->ops->start_link) {
+			/* Ignore errors, the link may come up later */
+			dw_pcie_wait_for_link(pci);
+		}
+	}
 
 	bridge->sysdata = pp;
 
-- 
2.43.0.429.g432eaa2c6b-goog