linux-kernel - RE: [PATCH v14 11/17] PCI: imx6: Move regulator enable out of imx6_pcie_deassert_core

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Date:   Wed, 13 Jul 2022 10:57:10 +0000
From:   Hongxing Zhu <hongxing.zhu@....com>
To:     Lucas Stach <l.stach@...gutronix.de>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "festevam@...il.com" <festevam@...il.com>,
        "francesco.dolcini@...adex.com" <francesco.dolcini@...adex.com>
CC:     "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 v14 11/17] PCI: imx6: Move regulator enable out of
 imx6_pcie_deassert_core_reset()

> -----Original Message-----
> From: Lucas Stach <l.stach@...gutronix.de>
> Sent: 2022年7月13日 16:41
> To: Hongxing Zhu <hongxing.zhu@....com>; bhelgaas@...gle.com;
> robh+dt@...nel.org; broonie@...nel.org; lorenzo.pieralisi@....com;
> festevam@...il.com; francesco.dolcini@...adex.com
> Cc: 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 v14 11/17] PCI: imx6: Move regulator enable out of
> imx6_pcie_deassert_core_reset()
> 
> Am Freitag, dem 01.07.2022 um 11:25 +0800 schrieb Richard Zhu:
> > Move regulator enable out of imx6_pcie_deassert_core_reset(), since
> > the
> > regulator_enable() has nothing to do in with
> > imx6_pcie_deassert_core_reset().
> >
> > Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> 
> Ah, so you are doing things in two steps. Disregard my first comment on the
> last patch then.
Thanks.

> 
> > ---
> >  drivers/pci/controller/dwc/pci-imx6.c | 36
> > ++++++++++++---------------
> >  1 file changed, 16 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index f72eb609769b..0b168f0d57b8 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -712,19 +712,10 @@ static int imx6_pcie_deassert_core_reset(struct
> imx6_pcie *imx6_pcie)
> >  	struct device *dev = pci->dev;
> >  	int ret;
> >
> > -	if (imx6_pcie->vpcie) {
> > -		ret = regulator_enable(imx6_pcie->vpcie);
> > -		if (ret) {
> > -			dev_err(dev, "failed to enable vpcie regulator: %d\n",
> > -				ret);
> > -			return ret;
> > -		}
> > -	}
> > -
> >  	ret = imx6_pcie_clk_enable(imx6_pcie);
> >  	if (ret) {
> >  		dev_err(dev, "unable to enable pcie clocks: %d\n", ret);
> > -		goto err_clks;
> > +		return ret;
> >  	}
> >
> >  	switch (imx6_pcie->drvdata->variant) { @@ -783,15 +774,6 @@ static
> > int imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie)
> >  	}
> >
> >  	return 0;
> > -
> > -err_clks:
> > -	if (imx6_pcie->vpcie) {
> > -		ret = regulator_disable(imx6_pcie->vpcie);
> > -		if (ret)
> > -			dev_err(dev, "failed to disable vpcie regulator: %d\n",
> > -				ret);
> > -	}
> > -	return ret;
> >  }
> >
> >  static int imx6_pcie_wait_for_speed_change(struct imx6_pcie
> > *imx6_pcie) @@ -916,15 +898,29 @@ static int
> > imx6_pcie_host_init(struct pcie_port *pp)
> >
> >  	imx6_pcie_assert_core_reset(imx6_pcie);
> >  	imx6_pcie_init_phy(imx6_pcie);
> > +	if (imx6_pcie->vpcie) {
> > +		ret = regulator_enable(imx6_pcie->vpcie);
> > +		if (ret) {
> > +			dev_err(dev, "failed to enable vpcie regulator: %d\n",
> > +				ret);
> > +			return ret;
> 
> If the regulator enable fails, you don't roll back the PHY init and core reset. This
> seems harmless now, but might have unintended consequences if the PHY
> code changes. I think it should be safe to move the regulator enable before the
> PHY init and core reset assert to avoid introducing more failure cleanup paths
> here.
To keep the same behavior, I just place the regulator_enable() in front of
 imx6_pcie_deassert_core_reset(). 
It makes sense to move it earlier to avoid the possible failure cleanup of
 imx6_pcie_assert_core_reset() and imx6_pcie_init_phy() in future.

Best Regards
Richard
> 
> Regards,
> Lucas
> 
> > +		}
> > +	}
> > +
> >  	ret = imx6_pcie_deassert_core_reset(imx6_pcie);
> >  	if (ret < 0) {
> >  		dev_err(dev, "pcie deassert core reset failed: %d\n", ret);
> > -		return ret;
> > +		goto err_reg_disable;
> >  	}
> >
> >  	imx6_setup_phy_mpll(imx6_pcie);
> >
> >  	return 0;
> > +
> > +err_reg_disable:
> > +	if (imx6_pcie->vpcie)
> > +		regulator_disable(imx6_pcie->vpcie);
> > +	return ret;
> >  }
> >
> >  static const struct dw_pcie_host_ops imx6_pcie_host_ops = {
>