linux-kernel - Re: [PATCH v5] PCI: imx6: Enable the vpcie3v3aux regulator when fetch it

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Message-ID: <aKXj5IT9yEWYn6BG@lizhi-Precision-Tower-5810>
Date: Wed, 20 Aug 2025 11:04:04 -0400
From: Frank Li <Frank.li@....com>
To: Richard Zhu <hongxing.zhu@....com>
Cc: 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,
	linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	devicetree@...r.kernel.org, imx@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] PCI: imx6: Enable the vpcie3v3aux regulator when
 fetch it

On Wed, Aug 20, 2025 at 10:23:28AM +0800, Richard Zhu wrote:
> 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.
>
> When the 3.3V auxiliary power is present, fetch this auxiliary 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>

Reviewed-by: Frank Li <Frank.Li@....com>

> ---
> v5 changes:
> - Use the vpcie3v3aux property instead of adding a duplicated one.
> - Move the comments from the code changes into the description of
>   commit.
>
> v4 changes:
> Move the dt-binding to snps,dw-pcie-common.yaml.
>
> v3 changes:
> Add a new vaux power supply used to specify the regulator powered up the
> WAKE# circuit on the connector when WAKE# is supported.
>
> v2 changes:
> Update the commit message, and add reviewed-by from Frank.
> https://patchwork.kernel.org/project/linux-pci/patch/20250619072438.125921-1-hongxing.zhu@nxp.com/
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 5a38cfaf989b1..5067da14bc053 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -1739,6 +1739,10 @@ 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);
>
> +	ret = devm_regulator_get_enable_optional(&pdev->dev, "vpcie3v3aux");
> +	if (ret < 0 && ret != -ENODEV)
> +		return dev_err_probe(dev, ret, "failed to enable pcie3v3vaux");
> +
>  	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
>