linux-kernel - RE: [PATCH v4 2/2] PCI: imx6: Enable the vaux regulator when fetch it

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Message-ID:
 <DB9PR04MB8429F4EF7F195825C7004AB59230A@DB9PR04MB8429.eurprd04.prod.outlook.com>
Date: Tue, 19 Aug 2025 08:41:13 +0000
From: Sherry Sun <sherry.sun@....com>
To: Hongxing Zhu <hongxing.zhu@....com>, Frank Li <frank.li@....com>,
	"l.stach@...gutronix.de" <l.stach@...gutronix.de>, "lpieralisi@...nel.org"
	<lpieralisi@...nel.org>, "kwilczynski@...nel.org" <kwilczynski@...nel.org>,
	"mani@...nel.org" <mani@...nel.org>, "robh@...nel.org" <robh@...nel.org>,
	"krzk+dt@...nel.org" <krzk+dt@...nel.org>, "conor+dt@...nel.org"
	<conor+dt@...nel.org>, "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"shawnguo@...nel.org" <shawnguo@...nel.org>, "s.hauer@...gutronix.de"
	<s.hauer@...gutronix.de>, "kernel@...gutronix.de" <kernel@...gutronix.de>,
	"festevam@...il.com" <festevam@...il.com>
CC: "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>, "imx@...ts.linux.dev" <imx@...ts.linux.dev>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Hongxing Zhu
	<hongxing.zhu@....com>
Subject: RE: [PATCH v4 2/2] PCI: imx6: Enable the vaux regulator when fetch it



> -----Original Message-----
> From: Richard Zhu <hongxing.zhu@....com>
> Sent: Tuesday, August 19, 2025 3:17 PM
> To: Frank Li <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; Hongxing Zhu <hongxing.zhu@....com>
> Subject: [PATCH v4 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;

Hi Richard, this seems defined but not used?

Best Regards
Sherry

>  	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
>