linux-kernel - [PATCH v3 2/2] PCI: imx6: Enable the vaux regulator when fetch it

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Message-Id: <20250814085920.590101-3-hongxing.zhu@nxp.com>
Date: Thu, 14 Aug 2025 16:59:20 +0800
From: Richard Zhu <hongxing.zhu@....com>
To: frank.li@....com,
	l.stach@...gutronix.de,
	lpieralisi@...nel.org,
	kwilczynski@...nel.org,
	mani@...nel.org,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org,
	bhelgaas@...gle.com,
	shawnguo@...nel.org,
	s.hauer@...gutronix.de,
	kernel@...gutronix.de,
	festevam@...il.com
Cc: linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	devicetree@...r.kernel.org,
	imx@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Richard Zhu <hongxing.zhu@....com>
Subject: [PATCH v3 2/2] PCI: imx6: Enable the vaux regulator when fetch it

Enable the vaux regulator at probe time and keep it enabled for the
entire PCIe controller lifecycle. This ensures support for outbound
wake-up mechanism such as WAKE# signaling.

Signed-off-by: Richard Zhu <hongxing.zhu@....com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 5a38cfaf989b1..1c1dce2d87e44 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -159,6 +159,7 @@ struct imx_pcie {
 	u32			tx_deemph_gen2_6db;
 	u32			tx_swing_full;
 	u32			tx_swing_low;
+	struct regulator	*vaux;
 	struct regulator	*vpcie;
 	struct regulator	*vph;
 	void __iomem		*phy_base;
@@ -1739,6 +1740,20 @@ static int imx_pcie_probe(struct platform_device *pdev)
 	pci->max_link_speed = 1;
 	of_property_read_u32(node, "fsl,max-link-speed", &pci->max_link_speed);
 
+	/*
+	 * Refer to PCIe CEM r6.0, sec 2.3 WAKE# Signal, WAKE# signal is only
+	 * asserted by the Add-in Card when all its functions are in D3Cold
+	 * state and at least one of its functions is enabled for wakeup
+	 * generation. The 3.3V auxiliary power (+3.3Vaux) must be present and
+	 * used for wakeup process. Since the main power supply would be gated
+	 * off to let Add-in Card to be in D3Cold, get the vaux and keep it
+	 * enabled to power up WAKE# circuit for the entire PCIe controller
+	 * lifecycle when WAKE# is supported.
+	 */
+	ret = devm_regulator_get_enable_optional(&pdev->dev, "vaux");
+	if (ret < 0 && ret != -ENODEV)
+		return dev_err_probe(dev, ret, "failed to enable vaux");
+
 	imx_pcie->vpcie = devm_regulator_get_optional(&pdev->dev, "vpcie");
 	if (IS_ERR(imx_pcie->vpcie)) {
 		if (PTR_ERR(imx_pcie->vpcie) != -ENODEV)
-- 
2.37.1