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

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Message-ID:
 <DU2PR04MB8840BC4FB0436EB03B2C56338C35A@DU2PR04MB8840.eurprd04.prod.outlook.com>
Date: Thu, 14 Aug 2025 05:54:54 +0000
From: Hongxing Zhu <hongxing.zhu@....com>
To: Manivannan Sadhasivam <mani@...nel.org>
CC: 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>, "robh@...nel.org"
	<robh@...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>, "linux-pci@...r.kernel.org"
	<linux-pci@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "imx@...ts.linux.dev"
	<imx@...ts.linux.dev>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2] PCI: imx6: Enable the vpcie regulator when fetch it

> -----Original Message-----
> From: Manivannan Sadhasivam <mani@...nel.org>
> Sent: 2025年8月13日 1:12
> To: Hongxing Zhu <hongxing.zhu@....com>
> Cc: Frank Li <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.
Hi Mani:
Thanks for your comments. You're right.
Another +3.3Vaux should be added to power up the WAKE# circuit.

Best Regards
Richard Zhu
> 
> - 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
> >
> 
> --
> மணிவண்ணன் சதாசிவம்