linux-kernel - RE: [PATCH v7 7/8] PCI: imx6: Disable enabled clocks and regulators after link is down

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Date:   Thu, 24 Feb 2022 07:51:07 +0000
From:   Hongxing Zhu <hongxing.zhu@....com>
To:     Bjorn Helgaas <helgaas@...nel.org>
CC:     "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "jingoohan1@...il.com" <jingoohan1@...il.com>,
        "festevam@...il.com" <festevam@...il.com>,
        "francesco.dolcini@...adex.com" <francesco.dolcini@...adex.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH v7 7/8] PCI: imx6: Disable enabled clocks and regulators
 after link is down

> -----Original Message-----
> From: Bjorn Helgaas <helgaas@...nel.org>
> Sent: 2022年2月24日 1:50
> To: Hongxing Zhu <hongxing.zhu@....com>
> Cc: l.stach@...gutronix.de; bhelgaas@...gle.com; broonie@...nel.org;
> lorenzo.pieralisi@....com; jingoohan1@...il.com; festevam@...il.com;
> francesco.dolcini@...adex.com; linux-pci@...r.kernel.org;
> linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org;
> kernel@...gutronix.de; dl-linux-imx <linux-imx@....com>
> Subject: Re: [PATCH v7 7/8] PCI: imx6: Disable enabled clocks and regulators
> after link is down
> 
> In subject,
> 
> s/Disable enabled clocks/Disable clocks/
Okay, would be updated later.
Thanks.

> 
> On Wed, Feb 16, 2022 at 02:21:02PM +0800, Richard Zhu wrote:
> > Since i.MX PCIe doesn't support the hot-plug, and to save power
> > consumption as much as possible. Return error and disable the enabled
> > clocks and regulators when link is down,.
> 
> Maybe:
> 
>   Since i.MX PCIe doesn't support hot-plug, reduce power consumption
>   as much as possible by disabling clocks and regulators and returning
>   error when the link is down.
Okay.

> 
> > Add a new host_exit() callback for i.MX PCIe driver to disable the
> > enabled clocks, regulators and so on in the error handling after
> > host_init is finished.
> >
> > Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> > ---
> >  drivers/pci/controller/dwc/pci-imx6.c | 30
> > ++++++++++++++++++++++++---
> >  1 file changed, 27 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index 242d8ef73c1e..fe671e88ec93 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -848,7 +848,9 @@ static int imx6_pcie_start_link(struct dw_pcie *pci)
> >  	/* Start LTSSM. */
> >  	imx6_pcie_ltssm_enable(dev);
> >
> > -	dw_pcie_wait_for_link(pci);
> > +	ret = dw_pcie_wait_for_link(pci);
> > +	if (ret)
> > +		goto err_reset_phy;
> 
> These labels look wrong now, since you no longer reset the PHY at
> err_reset_phy.
You're right. Would be replaced by "err_out" later.
Thanks.

Best Regards
Richard Zhu

> 
> >  	if (pci->link_gen == 2) {
> >  		/* Allow Gen2 mode after the link is up. */ @@ -884,7 +886,9 @@
> > static int imx6_pcie_start_link(struct dw_pcie *pci)
> >  		}
> >
> >  		/* Make sure link training is finished as well! */
> > -		dw_pcie_wait_for_link(pci);
> > +		ret = dw_pcie_wait_for_link(pci);
> > +		if (ret)
> > +			goto err_reset_phy;
> >  	} else {
> >  		dev_info(dev, "Link: Gen2 disabled\n");
> >  	}
> > @@ -897,7 +901,6 @@ static int imx6_pcie_start_link(struct dw_pcie *pci)
> >  	dev_dbg(dev, "PHY DEBUG_R0=0x%08x DEBUG_R1=0x%08x\n",
> >  		dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0),
> >  		dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG1));
> > -	imx6_pcie_reset_phy(imx6_pcie);
> >  	return ret;
> >  }
> >
> > @@ -921,8 +924,29 @@ static int imx6_pcie_host_init(struct pcie_port *pp)
> >  	return 0;
> >  }
> >
> > +static void imx6_pcie_host_exit(struct pcie_port *pp) {
> > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > +	struct device *dev = pci->dev;
> > +	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pci);
> > +
> > +	imx6_pcie_reset_phy(imx6_pcie);
> > +	imx6_pcie_clk_disable(imx6_pcie);
> > +	switch (imx6_pcie->drvdata->variant) {
> > +	case IMX8MM:
> > +		if (phy_power_off(imx6_pcie->phy))
> > +			dev_err(dev, "unable to power off phy\n");
> > +		break;
> > +	default:
> > +		break;
> > +	}
> > +	if (imx6_pcie->vpcie)
> > +		regulator_disable(imx6_pcie->vpcie);
> > +}
> > +
> >  static const struct dw_pcie_host_ops imx6_pcie_host_ops = {
> >  	.host_init = imx6_pcie_host_init,
> > +	.host_exit = imx6_pcie_host_exit,
> >  };
> >
> >  static const struct dw_pcie_ops dw_pcie_ops = {
> > --
> > 2.25.1
> >