linux-kernel - Re: [PATCH v1 1/4] usb: ehci-exynos: Use devm_clk_get

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Message-ID: <d3c72bbf-2dd2-4d7f-9882-08710baa3f3a@rowland.harvard.edu>
Date: Fri, 1 Mar 2024 15:19:47 -0500
From: Alan Stern <stern@...land.harvard.edu>
To: Anand Moon <linux.amoon@...il.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
  Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
  Alim Akhtar <alim.akhtar@...sung.com>, linux-usb@...r.kernel.org,
  linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org,
  linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/4] usb: ehci-exynos: Use devm_clk_get_enabled()
 helpers

On Sat, Mar 02, 2024 at 01:08:08AM +0530, Anand Moon wrote:
> The devm_clk_get_enabled() helpers:
>     - call devm_clk_get()
>     - call clk_prepare_enable() and register what is needed in order to
>      call clk_disable_unprepare() when needed, as a managed resource.
> 
> This simplifies the code and avoids the calls to clk_disable_unprepare().
> 
> While at it, use dev_err_probe consistently, and use its return value
> to return the error code.
> 
> Signed-off-by: Anand Moon <linux.amoon@...il.com>
> ---
>  drivers/usb/host/ehci-exynos.c | 30 +++++-------------------------
>  1 file changed, 5 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/usb/host/ehci-exynos.c b/drivers/usb/host/ehci-exynos.c
> index f644b131cc0b..05aa3d9c2a3b 100644
> --- a/drivers/usb/host/ehci-exynos.c
> +++ b/drivers/usb/host/ehci-exynos.c
> @@ -159,19 +159,12 @@ static int exynos_ehci_probe(struct platform_device *pdev)
>  
>  	err = exynos_ehci_get_phy(&pdev->dev, exynos_ehci);
>  	if (err)
> -		goto fail_clk;
> -
> -	exynos_ehci->clk = devm_clk_get(&pdev->dev, "usbhost");
> -
> -	if (IS_ERR(exynos_ehci->clk)) {
> -		dev_err(&pdev->dev, "Failed to get usbhost clock\n");
> -		err = PTR_ERR(exynos_ehci->clk);
> -		goto fail_clk;
> -	}
> +		goto fail_io;
>  
> -	err = clk_prepare_enable(exynos_ehci->clk);
> -	if (err)
> -		goto fail_clk;
> +	exynos_ehci->clk = devm_clk_get_enabled(&pdev->dev, "usbhost");
> +	if (IS_ERR(exynos_ehci->clk))
> +		return dev_err_probe(&pdev->dev, PTR_ERR(exynos_ehci->clk),
> +				  "Failed to get usbhost clock\n");

What about the usb_put_hcd(hcd) call that used to happen here?

Alan Stern

>  
>  	hcd->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
>  	if (IS_ERR(hcd->regs)) {
> @@ -223,8 +216,6 @@ static int exynos_ehci_probe(struct platform_device *pdev)
>  	exynos_ehci_phy_disable(&pdev->dev);
>  	pdev->dev.of_node = exynos_ehci->of_node;
>  fail_io:
> -	clk_disable_unprepare(exynos_ehci->clk);
> -fail_clk:
>  	usb_put_hcd(hcd);
>  	return err;
>  }
> @@ -240,8 +231,6 @@ static void exynos_ehci_remove(struct platform_device *pdev)
>  
>  	exynos_ehci_phy_disable(&pdev->dev);
>  
> -	clk_disable_unprepare(exynos_ehci->clk);
> -
>  	usb_put_hcd(hcd);
>  }
>  
> @@ -249,7 +238,6 @@ static void exynos_ehci_remove(struct platform_device *pdev)
>  static int exynos_ehci_suspend(struct device *dev)
>  {
>  	struct usb_hcd *hcd = dev_get_drvdata(dev);
> -	struct exynos_ehci_hcd *exynos_ehci = to_exynos_ehci(hcd);
>  
>  	bool do_wakeup = device_may_wakeup(dev);
>  	int rc;
> @@ -260,25 +248,17 @@ static int exynos_ehci_suspend(struct device *dev)
>  
>  	exynos_ehci_phy_disable(dev);
>  
> -	clk_disable_unprepare(exynos_ehci->clk);
> -
>  	return rc;
>  }
>  
>  static int exynos_ehci_resume(struct device *dev)
>  {
>  	struct usb_hcd *hcd = dev_get_drvdata(dev);
> -	struct exynos_ehci_hcd *exynos_ehci = to_exynos_ehci(hcd);
>  	int ret;
>  
> -	ret = clk_prepare_enable(exynos_ehci->clk);
> -	if (ret)
> -		return ret;
> -
>  	ret = exynos_ehci_phy_enable(dev);
>  	if (ret) {
>  		dev_err(dev, "Failed to enable USB phy\n");
> -		clk_disable_unprepare(exynos_ehci->clk);
>  		return ret;
>  	}
>  
> -- 
> 2.43.0
>