linux-kernel - [PATCH v2] PCI: dwc: Wait for link up only if link is started

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Message-ID: <20230227201340.2087605-1-sdalvi@google.com>
Date:   Mon, 27 Feb 2023 14:13:40 -0600
From:   Sajid Dalvi <sdalvi@...gle.com>
To:     Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        "Krzysztof Wilczyński" <kw@...ux.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Sajid Dalvi <sdalvi@...gle.com>, kernel-team@...roid.com,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] PCI: dwc: Wait for link up only if link is started

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 1
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.

Call trace when start_link() is not defined:
dw_pcie_wait_for_link << spins in a loop for 1 second
dw_pcie_host_init

Signed-off-by: Sajid Dalvi <sdalvi@...gle.com>
---
 drivers/pci/controller/dwc/pcie-designware-host.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 9952057c8819..9709f69f173e 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -489,10 +489,10 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
 		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);
+		/* Ignore errors, the link may come up later */
+		dw_pcie_wait_for_link(pci);
+	}
 
 	bridge->sysdata = pp;
 
-- 
2.39.2.722.g9855ee24e9-goog