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 10:41:07 +0200
From:   Lucas Stach <l.stach@...gutronix.de>
To:     Richard 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,
        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.

> ---
>  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.

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 = {