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Date:   Wed, 15 Jun 2022 18:30:34 -0500
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Richard Zhu <hongxing.zhu@nxp.com>,
        Lucas Stach <l.stach@pengutronix.de>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Brown <broonie@kernel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Fabio Estevam <festevam@gmail.com>,
        Francesco Dolcini <francesco.dolcini@toradex.com>
Cc:     linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, kernel@pengutronix.de,
        linux-imx@nxp.com, Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [PATCH v12 09/13] PCI: imx6: Turn off regulator when system is
 in suspend mode
Message-ID: <20220615233034.GA1056086@bhelgaas>
MIME-Version: 1.0
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In-Reply-To: <20220615231551.1054753-10-helgaas@kernel.org>
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On Wed, Jun 15, 2022 at 06:15:47PM -0500, Bjorn Helgaas wrote:
> From: Richard Zhu <hongxing.zhu@nxp.com>
> 
> The driver should undo any enables it did itself. The regulator disable
> shouldn't be basing decisions on regulator_is_enabled().
> 
> Move the regulator_disable to the suspend function, turn off regulator when
> the system is in suspend mode.
> 
> To keep the balance of the regulator usage counter, disable the regulator
> in shutdown.
> 
> Link: https://lore.kernel.org/r/1655189942-12678-6-git-send-email-hongxing.z
> hu@nxp.com
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.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 6eddd0b5f628..537b8a2e0e3b 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -670,8 +670,6 @@ static void imx6_pcie_clk_disable(struct imx6_pcie *imx6_pcie)
>  
>  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:
> @@ -702,14 +700,6 @@ static void imx6_pcie_assert_core_reset(struct imx6_pcie *imx6_pcie)
>  		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);
> -	}
> -
>  	/* Some boards don't have PCIe reset GPIO. */
>  	if (gpio_is_valid(imx6_pcie->reset_gpio))
>  		gpio_set_value_cansleep(imx6_pcie->reset_gpio,
> @@ -722,7 +712,7 @@ 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",
> @@ -796,7 +786,7 @@ 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",
> @@ -1023,6 +1013,9 @@ static int imx6_pcie_suspend_noirq(struct device *dev)
>  		break;
>  	}
>  
> +	if (imx6_pcie->vpcie)
> +		regulator_disable(imx6_pcie->vpcie);

This is a little bit ugly because imx6_pcie_suspend_noirq() and
imx6_pcie_resume_noirq() are not symmetric.

We call regulator_disable() directly here in
imx6_pcie_suspend_noirq(), but the corresponding regulator_enable() is
buried in imx6_pcie_deassert_core_reset().

It would be nicer if the suspend and resume paths looked more similar,
as rockchip_pcie_suspend_noirq() and rockchip_pcie_resume_noirq() do,
for example.

>  	return 0;
>  }
>  
> @@ -1269,6 +1262,8 @@ 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[] = {
> -- 
> 2.25.1
> 
> 
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