linux-kernel - Re: [PATCH 3/3 v3] USB: ehci-s5p: Add vbus setup function to the s5p ehci glue layer

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Message-ID: <Pine.LNX.4.44L0.1207161008520.1660-100000@iolanthe.rowland.org>
Date:	Mon, 16 Jul 2012 10:10:02 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Vivek Gautam <gautam.vivek@...sung.com>
cc:	linux-usb@...r.kernel.org, <linux-kernel@...r.kernel.org>,
	<devicetree-discuss@...ts.ozlabs.org>, <l.majewski@...sung.com>,
	<a.kesavan@...sung.com>, <prashanth.g@...sung.com>,
	<kmpark@...radead.org>, <joshi@...sung.com>, <olofj@...gle.com>,
	<jg1.han@...sung.com>, <jy0922.shim@...sung.com>,
	<thomas.abraham@...aro.org>, <sshtylyov@...sta.com>
Subject: Re: [PATCH 3/3 v3] USB: ehci-s5p: Add vbus setup function to the
 s5p ehci glue layer

On Mon, 16 Jul 2012, Vivek Gautam wrote:

> This patch retrieves and configures the vbus control gpio via
> the device tree. The suspend/resume callbacks will be later
> modified for vbus control.
> 
> Signed-off-by: Abhilash Kesavan <a.kesavan@...sung.com>
> Signed-off-by: Vivek Gautam <gautam.vivek@...sung.com>
> 
> diff --git a/drivers/usb/host/ehci-s5p.c b/drivers/usb/host/ehci-s5p.c
> index 37d84cf..4037878 100644
> --- a/drivers/usb/host/ehci-s5p.c
> +++ b/drivers/usb/host/ehci-s5p.c
> @@ -15,6 +15,7 @@
>  #include <linux/clk.h>
>  #include <linux/of.h>
>  #include <linux/platform_device.h>
> +#include <linux/of_gpio.h>
>  #include <plat/ehci.h>
>  #include <plat/usb-phy.h>
>  
> @@ -64,6 +65,28 @@ static const struct hc_driver s5p_ehci_hc_driver = {
>  	.clear_tt_buffer_complete	= ehci_clear_tt_buffer_complete,
>  };
>  
> +static int s5p_ehci_setup_gpio(struct platform_device *pdev)
> +{
> +	int err;
> +	int gpio;
> +
> +	if (!pdev->dev.of_node)
> +		return 0;
> +
> +	gpio = of_get_named_gpio(pdev->dev.of_node,
> +			"samsung,vbus-gpio", 0);
> +	if (!gpio_is_valid(gpio))
> +		return 0;
> +
> +	err = gpio_request_one(gpio, GPIOF_OUT_INIT_HIGH, "ehci_vbus_gpio");
> +	if (err) {
> +		dev_err(&pdev->dev, "can't request ehci vbus gpio %d", gpio);
> +		return err;

This "return" statement is unnecessary.

> +	}
> +
> +	return err;
> +}
> +
>  static u64 ehci_s5p_dma_mask = DMA_BIT_MASK(32);
>  
>  static int __devinit s5p_ehci_probe(struct platform_device *pdev)
> @@ -92,6 +115,8 @@ static int __devinit s5p_ehci_probe(struct platform_device *pdev)
>  	if (!pdev->dev.coherent_dma_mask)
>  		pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
>  
> +	s5p_ehci_setup_gpio(pdev);

Why does the function return an error code if that error code is just 
going to be ignored?

Alan Stern

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