linux-kernel - [PATCH v2 1/2] PCI: qcom: Skip wait for link up if global IRQ handler is present

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Message-ID: <20240920-remove_wait-v2-1-7c0fcb3b581d@quicinc.com>
Date: Fri, 20 Sep 2024 15:47:59 +0530
From: Krishna chaitanya chundru <quic_krichai@...cinc.com>
To: Jingoo Han <jingoohan1@...il.com>,
        Manivannan Sadhasivam
	<manivannan.sadhasivam@...aro.org>,
        Lorenzo Pieralisi
	<lpieralisi@...nel.org>,
        Krzysztof Wilczyński
	<kw@...ux.com>,
        Rob Herring <robh@...nel.org>, Bjorn Helgaas
	<bhelgaas@...gle.com>
CC: <quic_vbadigan@...cinc.com>, <quic_ramkri@...cinc.com>,
        <quic_nitegupt@...cinc.com>, <quic_skananth@...cinc.com>,
        <quic_vpernami@...cinc.com>, <quic_mrana@...cinc.com>,
        <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>,
        Krishna chaitanya chundru
	<quic_krichai@...cinc.com>
Subject: [PATCH v2 1/2] PCI: qcom: Skip wait for link up if global IRQ
 handler is present

In cases where a global IRQ handler is present to manage link up
interrupts, it may not be necessary to wait for the link to be up
during PCI initialization which optimizes the bootup time.

Move platform_get_irq_byname_optional() above to set linkup_irq
before dw_pcie_host_init() as this flag is used in this function only.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
---
 drivers/pci/controller/dwc/pcie-designware-host.c | 11 +++++++++--
 drivers/pci/controller/dwc/pcie-designware.h      |  1 +
 drivers/pci/controller/dwc/pcie-qcom.c            |  5 ++++-
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 3e41865c7290..b7d20a1bab0a 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -530,8 +530,15 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
 			goto err_remove_edma;
 	}
 
-	/* Ignore errors, the link may come up later */
-	dw_pcie_wait_for_link(pci);
+	/*
+	 * Note: The link up delay is skipped only when a link up IRQ is present.
+	 * This flag should not be used to bypass the link up delay for arbitrary
+	 * reasons.
+	 *
+	 * Ignore errors, the link may come up later.
+	 */
+	if (!pp->linkup_irq)
+		dw_pcie_wait_for_link(pci);
 
 	bridge->sysdata = pp;
 
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index e518f81ea80c..b850f0a74695 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -348,6 +348,7 @@ struct dw_pcie_rp {
 	bool			use_atu_msg;
 	int			msg_atu_index;
 	struct resource		*msg_res;
+	bool			linkup_irq;
 };
 
 struct dw_pcie_ep_ops {
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 88a98be930e3..905c9154fc65 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1686,6 +1686,10 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, pcie);
 
+	irq = platform_get_irq_byname_optional(pdev, "global");
+	if (irq > 0)
+		pp->linkup_irq = true;
+
 	ret = dw_pcie_host_init(pp);
 	if (ret) {
 		dev_err(dev, "cannot initialize host\n");
@@ -1699,7 +1703,6 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 		goto err_host_deinit;
 	}
 
-	irq = platform_get_irq_byname_optional(pdev, "global");
 	if (irq > 0) {
 		ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
 						qcom_pcie_global_irq_thread,

-- 
2.34.1