linux-kernel - Re: [PATCH v9 5/8] PCI: imx6: Refine the regulator usage

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Message-ID: <2427cef355dc1b9d1667a2c80448d2e23b97c447.camel@pengutronix.de>
Date:   Wed, 08 Jun 2022 09:26:58 +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,
        jingoohan1@...il.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 v9 5/8] PCI: imx6: Refine the regulator usage

Am Freitag, dem 06.05.2022 um 09:47 +0800 schrieb Richard Zhu:
> The driver should undo any enables it did itself. The regulator disable
> shouldn't be basing decisions on regulator_is_enabled().
> 
> To keep the balance of the regulator usage counter, disable the regulator
> just behind of imx6_pcie_assert_core_reset() in resume and shutdown.
> 
> Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 19 +++++++------------
>  1 file changed, 7 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 7005a7910003..3ce3993d5797 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -369,8 +369,6 @@ static int imx6_pcie_attach_pd(struct device *dev)
>  
>  static void imx6_pcie_assert_core_reset(struct imx6_pcie *imx6_pcie)
>  {
> -	struct device *dev = imx6_pcie->pci->dev;
> -
>  	switch (imx6_pcie->drvdata->variant) {
>  	case IMX7D:
>  	case IMX8MQ:
> @@ -400,14 +398,6 @@ static void imx6_pcie_assert_core_reset(struct imx6_pcie *imx6_pcie)
>  				   IMX6Q_GPR1_PCIE_REF_CLK_EN, 0 << 16);
>  		break;
>  	}
> -
> -	if (imx6_pcie->vpcie && regulator_is_enabled(imx6_pcie->vpcie) > 0) {
> -		int ret = regulator_disable(imx6_pcie->vpcie);
> -
> -		if (ret)
> -			dev_err(dev, "failed to disable vpcie regulator: %d\n",
> -				ret);
> -	}
>  }
>  
>  static unsigned int imx6_pcie_grp_offset(const struct imx6_pcie *imx6_pcie)
> @@ -580,7 +570,7 @@ static int imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie)
>  	struct device *dev = pci->dev;
>  	int ret, err;
>  
> -	if (imx6_pcie->vpcie && !regulator_is_enabled(imx6_pcie->vpcie)) {
> +	if (imx6_pcie->vpcie) {
>  		ret = regulator_enable(imx6_pcie->vpcie);
>  		if (ret) {
>  			dev_err(dev, "failed to enable vpcie regulator: %d\n",
> @@ -653,7 +643,7 @@ static int imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie)
>  	return 0;
>  
>  err_clks:
> -	if (imx6_pcie->vpcie && regulator_is_enabled(imx6_pcie->vpcie) > 0) {
> +	if (imx6_pcie->vpcie) {
>  		ret = regulator_disable(imx6_pcie->vpcie);
>  		if (ret)
>  			dev_err(dev, "failed to disable vpcie regulator: %d\n",
> @@ -1026,6 +1016,9 @@ static int imx6_pcie_resume_noirq(struct device *dev)
>  		return 0;
>  
>  	imx6_pcie_assert_core_reset(imx6_pcie);
> +	if (imx6_pcie->vpcie)
> +		regulator_disable(imx6_pcie->vpcie);
> +
This one looks misplaced. Surely you want the regulator to be on when
resuming the PCIe subsystem. Isn't this just papering over a wrong
usage count here, because there is no regulator_disable in
imx6_pcie_suspend_noirq, where I would expect this to happen?

Regards,
Lucas

>  	imx6_pcie_init_phy(imx6_pcie);
>  	imx6_pcie_deassert_core_reset(imx6_pcie);
>  	dw_pcie_setup_rc(pp);
> @@ -1259,6 +1252,8 @@ static void imx6_pcie_shutdown(struct platform_device *pdev)
>  
>  	/* bring down link, so bootloader gets clean state in case of reboot */
>  	imx6_pcie_assert_core_reset(imx6_pcie);
> +	if (imx6_pcie->vpcie)
> +		regulator_disable(imx6_pcie->vpcie);
>  }
>  
>  static const struct imx6_pcie_drvdata drvdata[] = {