linux-kernel - Re: [PATCH 1/4] PCI: imx6: Add pci host wakeup support on imx platforms.

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Message-ID: <0cd40cf388e70b101b3857220fd7a74cf75cfa81.camel@pengutronix.de>
Date:   Fri, 08 Dec 2023 11:16:23 +0100
From:   Lucas Stach <l.stach@...gutronix.de>
To:     Sherry Sun <sherry.sun@....com>, hongxing.zhu@....com,
        lpieralisi@...nel.org, kw@...ux.com, robh@...nel.org,
        bhelgaas@...gle.com, krzysztof.kozlowski+dt@...aro.org,
        conor+dt@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
        kernel@...gutronix.de, festevam@...il.com
Cc:     linux-imx@....com, linux-pci@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] PCI: imx6: Add pci host wakeup support on imx
 platforms.

Am Freitag, dem 08.12.2023 um 17:13 +0800 schrieb Sherry Sun:
> Add pci host wakeup feature for imx platforms.
> Example of configuring the corresponding dts property under the PCI
> node:
> host-wake-gpio = <&gpio5 21 GPIO_ACTIVE_LOW>;
> 
> Signed-off-by: Sherry Sun <sherry.sun@....com>
> Reviewed-by: Richard Zhu <hongxing.zhu@....com>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 69 +++++++++++++++++++++++++++
>  1 file changed, 69 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 74703362aeec..050c9140f4a3 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -72,6 +72,7 @@ struct imx6_pcie_drvdata {
>  struct imx6_pcie {
>  	struct dw_pcie		*pci;
>  	int			reset_gpio;
> +	int			host_wake_irq;
>  	bool			gpio_active_high;
>  	bool			link_is_up;
>  	struct clk		*pcie_bus;
> @@ -1237,11 +1238,46 @@ static int imx6_pcie_resume_noirq(struct device *dev)
>  	return 0;
>  }
>  
> +static int imx6_pcie_suspend(struct device *dev)
> +{
> +	struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
> +
> +	if (imx6_pcie->host_wake_irq >= 0)
> +		enable_irq_wake(imx6_pcie->host_wake_irq);
> +
> +	return 0;
> +}
> +
> +static int imx6_pcie_resume(struct device *dev)
> +{
> +	struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
> +
> +	if (imx6_pcie->host_wake_irq >= 0)
> +		disable_irq_wake(imx6_pcie->host_wake_irq);
> +
> +	return 0;
> +}
> +
>  static const struct dev_pm_ops imx6_pcie_pm_ops = {
>  	NOIRQ_SYSTEM_SLEEP_PM_OPS(imx6_pcie_suspend_noirq,
>  				  imx6_pcie_resume_noirq)
> +	SYSTEM_SLEEP_PM_OPS(imx6_pcie_suspend, imx6_pcie_resume)
>  };
>  
> +irqreturn_t host_wake_irq_handler(int irq, void *priv)
> +{
> +	struct imx6_pcie *imx6_pcie = priv;
> +	struct device *dev = imx6_pcie->pci->dev;
> +
> +	dev_dbg(dev, "%s: host wakeup by pcie", __func__);
> +
Not sure how much value this debug print carries. If you want to keep
it, drop the __func__. There is no other place in this driver handling
the wakeup, so the function name in the print is pure noise.

> +	/* Notify PM core we are wakeup source */
> +	pm_wakeup_event(dev, 0);
> +	pm_system_wakeup();
> +
> +	return IRQ_HANDLED;
> +}
> +
>  static int imx6_pcie_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -1250,6 +1286,7 @@ static int imx6_pcie_probe(struct platform_device *pdev)
>  	struct device_node *np;
>  	struct resource *dbi_base;
>  	struct device_node *node = dev->of_node;
> +	struct gpio_desc *host_wake_gpio;
>  	int ret;
>  	u16 val;
>  
> @@ -1457,6 +1494,32 @@ static int imx6_pcie_probe(struct platform_device *pdev)
>  			val |= PCI_MSI_FLAGS_ENABLE;
>  			dw_pcie_writew_dbi(pci, offset + PCI_MSI_FLAGS, val);
>  		}
> +
> +		/* host wakeup support */
> +		imx6_pcie->host_wake_irq = -1;
> +		host_wake_gpio = devm_gpiod_get_optional(dev, "host-wake", GPIOD_IN);
> +		if (IS_ERR(host_wake_gpio))
> +			return PTR_ERR(host_wake_gpio);
> +
> +		if (host_wake_gpio != NULL) {
> +			imx6_pcie->host_wake_irq = gpiod_to_irq(host_wake_gpio);
> +			ret = devm_request_threaded_irq(dev, imx6_pcie->host_wake_irq, NULL,
> +							host_wake_irq_handler,
> +							IRQF_ONESHOT | IRQF_TRIGGER_FALLING,
> +							"host_wake", imx6_pcie);
> +			if (ret) {
> +				dev_err(dev, "Failed to request host_wake_irq %d (%d)\n",
> +					imx6_pcie->host_wake_irq, ret);
> +				imx6_pcie->host_wake_irq = -1;

What's the point of resetting host_wake_irq to -1 in those error paths?
Nobody is going to access this member anymore after the error. Just
drop this.

You could simplify all those error paths to
if (err)
    return dev_err_probe(...);

> +				return ret;
> +			}
> +
> +			if (device_init_wakeup(dev, true)) {
> +				dev_err(dev, "fail to init host_wake_irq\n");
> +				imx6_pcie->host_wake_irq = -1;
> +				return ret;
> +			}
> +		}
>  	}
>  
>  	return 0;
> @@ -1466,6 +1529,12 @@ static void imx6_pcie_shutdown(struct platform_device *pdev)
>  {
>  	struct imx6_pcie *imx6_pcie = platform_get_drvdata(pdev);
>  
> +	if (imx6_pcie->host_wake_irq >= 0) {
> +		device_init_wakeup(&pdev->dev, false);
> +		disable_irq(imx6_pcie->host_wake_irq);
> +		imx6_pcie->host_wake_irq = -1;
> +	}
> +
>  	/* bring down link, so bootloader gets clean state in case of reboot */
>  	imx6_pcie_assert_core_reset(imx6_pcie);
>  }