linux-kernel - [PATCH v8 3/7] PCI: qcom: Add ICC bandwidth vote for CPU to PCIe path

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Message-ID: <20240302-opp_support-v8-3-158285b86b10@quicinc.com>
Date: Sat, 2 Mar 2024 09:29:57 +0530
From: Krishna chaitanya chundru <quic_krichai@...cinc.com>
To: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio
	<konrad.dybcio@...aro.org>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rob Herring
	<robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
        Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Rob Herring
	<robh+dt@...nel.org>,
        Johan Hovold <johan+linaro@...nel.org>,
        Brian Masney
	<bmasney@...hat.com>, Georgi Djakov <djakov@...nel.org>
CC: <linux-arm-msm@...r.kernel.org>, <linux-pci@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <vireshk@...nel.org>, <quic_vbadigan@...cinc.com>,
        <quic_skananth@...cinc.com>, <quic_nitegupt@...cinc.com>,
        <quic_parass@...cinc.com>,
        Krishna chaitanya chundru
	<quic_krichai@...cinc.com>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Subject: [PATCH v8 3/7] PCI: qcom: Add ICC bandwidth vote for CPU to PCIe
 path

To access PCIe registers, PCIe BAR space, config space the CPU-PCIe
ICC (interconnect consumers) path should be voted otherwise it may
lead to NoC (Network on chip) timeout. We are surviving because of
other driver vote for this path.

As there is less access on this path compared to PCIe to mem path
add minimum vote i.e 1KBps bandwidth always.

When suspending, disable this path after register space access
is done.

Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 38 ++++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 10f2d0bb86be..a0266bfe71f1 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -240,6 +240,7 @@ struct qcom_pcie {
 	struct phy *phy;
 	struct gpio_desc *reset;
 	struct icc_path *icc_mem;
+	struct icc_path *icc_cpu;
 	const struct qcom_pcie_cfg *cfg;
 	struct dentry *debugfs;
 	bool suspended;
@@ -1372,6 +1373,9 @@ static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
 	if (IS_ERR(pcie->icc_mem))
 		return PTR_ERR(pcie->icc_mem);
 
+	pcie->icc_cpu = devm_of_icc_get(pci->dev, "cpu-pcie");
+	if (IS_ERR(pcie->icc_cpu))
+		return PTR_ERR(pcie->icc_cpu);
 	/*
 	 * Some Qualcomm platforms require interconnect bandwidth constraints
 	 * to be set before enabling interconnect clocks.
@@ -1381,7 +1385,19 @@ static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
 	 */
 	ret = icc_set_bw(pcie->icc_mem, 0, QCOM_PCIE_LINK_SPEED_TO_BW(1));
 	if (ret) {
-		dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
+		dev_err(pci->dev, "failed to set interconnect bandwidth for pcie-mem: %d\n",
+			ret);
+		return ret;
+	}
+
+	/*
+	 * The config space, BAR space and registers goes through cpu-pcie path
+	 * Set peak bandwidth to 1KBps as recommended by HW team for this path
+	 * all the time.
+	 */
+	ret = icc_set_bw(pcie->icc_cpu, 0, kBps_to_icc(1));
+	if (ret) {
+		dev_err(pci->dev, "failed to set interconnect bandwidth for cpu-pcie: %d\n",
 			ret);
 		return ret;
 	}
@@ -1573,7 +1589,7 @@ static int qcom_pcie_suspend_noirq(struct device *dev)
 	 */
 	ret = icc_set_bw(pcie->icc_mem, 0, kBps_to_icc(1));
 	if (ret) {
-		dev_err(dev, "Failed to set interconnect bandwidth: %d\n", ret);
+		dev_err(dev, "Failed to set interconnect bandwidth for pcie-mem: %d\n", ret);
 		return ret;
 	}
 
@@ -1597,6 +1613,18 @@ static int qcom_pcie_suspend_noirq(struct device *dev)
 		pcie->suspended = true;
 	}
 
+	/* Remove CPU path vote after all the register access is done */
+	ret = icc_disable(pcie->icc_cpu);
+	if (ret) {
+		dev_err(dev, "failed to disable icc path of cpu-pcie: %d\n", ret);
+		if (pcie->suspended) {
+			qcom_pcie_host_init(&pcie->pci->pp);
+			pcie->suspended = false;
+		}
+		qcom_pcie_icc_update(pcie);
+		return ret;
+	}
+
 	return 0;
 }
 
@@ -1605,6 +1633,12 @@ static int qcom_pcie_resume_noirq(struct device *dev)
 	struct qcom_pcie *pcie = dev_get_drvdata(dev);
 	int ret;
 
+	ret = icc_enable(pcie->icc_cpu);
+	if (ret) {
+		dev_err(dev, "failed to enable icc path of cpu-pcie: %d\n", ret);
+		return ret;
+	}
+
 	if (pcie->suspended) {
 		ret = qcom_pcie_host_init(&pcie->pci->pp);
 		if (ret)

-- 
2.42.0