linux-kernel - Re: [PATCH v2] PCI: imx6: Enable the vpcie regulator when fetch it

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Message-ID: <zl6ie74kyeen2oudt3l2hv6ba5fwjsuiqlpdgaao5l7al7zjwu@bsj3agyukypn>
Date: Tue, 12 Aug 2025 22:42:17 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Richard Zhu <hongxing.zhu@....com>
Cc: frank.li@....com, l.stach@...gutronix.de, lpieralisi@...nel.org, 
	kwilczynski@...nel.org, robh@...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, imx@...ts.linux.dev, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] PCI: imx6: Enable the vpcie regulator when fetch it

On Thu, Jun 19, 2025 at 03:24:38PM GMT, Richard Zhu wrote:
> Enable the vpcie 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.

I'm not sure about this part. For supporting WAKE#, Vaux supply has to be
supplied to the endpoint. But here, 'vpcie' looks like the main 3.3V supply. So
keeping it always on to support WAKE#, sounds to me that the component never
enters the D3Cold state. So no WAKE# is required.

- Mani

> 
> Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 27 ++++-----------------------
>  1 file changed, 4 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 5a38cfaf989b..7cab4bcfae56 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -159,7 +159,6 @@ struct imx_pcie {
>  	u32			tx_deemph_gen2_6db;
>  	u32			tx_swing_full;
>  	u32			tx_swing_low;
> -	struct regulator	*vpcie;
>  	struct regulator	*vph;
>  	void __iomem		*phy_base;
>  
> @@ -1198,15 +1197,6 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
>  	struct imx_pcie *imx_pcie = to_imx_pcie(pci);
>  	int ret;
>  
> -	if (imx_pcie->vpcie) {
> -		ret = regulator_enable(imx_pcie->vpcie);
> -		if (ret) {
> -			dev_err(dev, "failed to enable vpcie regulator: %d\n",
> -				ret);
> -			return ret;
> -		}
> -	}
> -
>  	if (pp->bridge && imx_check_flag(imx_pcie, IMX_PCIE_FLAG_HAS_LUT)) {
>  		pp->bridge->enable_device = imx_pcie_enable_device;
>  		pp->bridge->disable_device = imx_pcie_disable_device;
> @@ -1222,7 +1212,7 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
>  	ret = imx_pcie_clk_enable(imx_pcie);
>  	if (ret) {
>  		dev_err(dev, "unable to enable pcie clocks: %d\n", ret);
> -		goto err_reg_disable;
> +		return ret;
>  	}
>  
>  	if (imx_pcie->phy) {
> @@ -1269,9 +1259,6 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
>  	phy_exit(imx_pcie->phy);
>  err_clk_disable:
>  	imx_pcie_clk_disable(imx_pcie);
> -err_reg_disable:
> -	if (imx_pcie->vpcie)
> -		regulator_disable(imx_pcie->vpcie);
>  	return ret;
>  }
>  
> @@ -1286,9 +1273,6 @@ static void imx_pcie_host_exit(struct dw_pcie_rp *pp)
>  		phy_exit(imx_pcie->phy);
>  	}
>  	imx_pcie_clk_disable(imx_pcie);
> -
> -	if (imx_pcie->vpcie)
> -		regulator_disable(imx_pcie->vpcie);
>  }
>  
>  static void imx_pcie_host_post_init(struct dw_pcie_rp *pp)
> @@ -1739,12 +1723,9 @@ 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);
>  
> -	imx_pcie->vpcie = devm_regulator_get_optional(&pdev->dev, "vpcie");
> -	if (IS_ERR(imx_pcie->vpcie)) {
> -		if (PTR_ERR(imx_pcie->vpcie) != -ENODEV)
> -			return PTR_ERR(imx_pcie->vpcie);
> -		imx_pcie->vpcie = NULL;
> -	}
> +	ret = devm_regulator_get_enable_optional(&pdev->dev, "vpcie");
> +	if (ret < 0 && ret != -ENODEV)
> +		return dev_err_probe(dev, ret, "failed to enable vpcie");
>  
>  	imx_pcie->vph = devm_regulator_get_optional(&pdev->dev, "vph");
>  	if (IS_ERR(imx_pcie->vph)) {
> -- 
> 2.37.1
> 

-- 
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