linux-kernel - [PATCH v1] PCI: imx6: Set MSI enable bit of RC in resume

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Date:   Tue,  1 Nov 2022 15:59:55 +0800
From:   Richard Zhu <hongxing.zhu@....com>
To:     l.stach@...gutronix.de, bhelgaas@...gle.com,
        lorenzo.pieralisi@....com
Cc:     hongxing.zhu@....com, linux-pci@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de, linux-imx@....com
Subject: [PATCH v1] PCI: imx6: Set MSI enable bit of RC in resume

The MSI Enable bit controls delivery of MSI interrupts from components
below the Root Port. This bit might lost during the suspend, should be
re-configured during resume.

Encapsulate the MSI enable set into a standalone function, and invoke it
in both probe and resume.

Signed-off-by: Richard Zhu <hongxing.zhu@....com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 2616585ca5f8..dba15546075f 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -1041,6 +1041,21 @@ static void imx6_pcie_pm_turnoff(struct imx6_pcie *imx6_pcie)
 	usleep_range(1000, 10000);
 }
 
+static void pci_imx_set_msi_en(struct dw_pcie *pci)
+{
+	u8 offset;
+	u16 val;
+
+	if (pci_msi_enabled()) {
+		offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);
+		dw_pcie_dbi_ro_wr_en(pci);
+		val = dw_pcie_readw_dbi(pci, offset + PCI_MSI_FLAGS);
+		val |= PCI_MSI_FLAGS_ENABLE;
+		dw_pcie_writew_dbi(pci, offset + PCI_MSI_FLAGS, val);
+		dw_pcie_dbi_ro_wr_dis(pci);
+	}
+}
+
 static int imx6_pcie_suspend_noirq(struct device *dev)
 {
 	struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
@@ -1073,6 +1088,7 @@ static int imx6_pcie_resume_noirq(struct device *dev)
 	if (imx6_pcie->link_is_up)
 		imx6_pcie_start_link(imx6_pcie->pci);
 
+	pci_imx_set_msi_en(imx6_pcie->pci);
 	return 0;
 }
 
@@ -1090,7 +1106,6 @@ static int imx6_pcie_probe(struct platform_device *pdev)
 	struct resource *dbi_base;
 	struct device_node *node = dev->of_node;
 	int ret;
-	u16 val;
 
 	imx6_pcie = devm_kzalloc(dev, sizeof(*imx6_pcie), GFP_KERNEL);
 	if (!imx6_pcie)
@@ -1282,12 +1297,7 @@ static int imx6_pcie_probe(struct platform_device *pdev)
 	if (ret < 0)
 		return ret;
 
-	if (pci_msi_enabled()) {
-		u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);
-		val = dw_pcie_readw_dbi(pci, offset + PCI_MSI_FLAGS);
-		val |= PCI_MSI_FLAGS_ENABLE;
-		dw_pcie_writew_dbi(pci, offset + PCI_MSI_FLAGS, val);
-	}
+	pci_imx_set_msi_en(pci);
 
 	return 0;
 }
-- 
2.25.1