linux-kernel - Re: [PATCH v3 3/4] usb: ohci-exynos: Add facility to use phy provided by the generic phy framework

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Message-ID: <Pine.LNX.4.44L0.1404281136440.1270-100000@iolanthe.rowland.org>
Date:	Mon, 28 Apr 2014 11:41:36 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Vivek Gautam <gautam.vivek@...sung.com>
cc:	linux-usb@...r.kernel.org, <linux-samsung-soc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<gregkh@...uxfoundation.org>, <balbi@...com>,
	<kgene.kim@...sung.com>, <k.debski@...sung.com>,
	Jingoo Han <jg1.han@...sung.com>
Subject: Re: [PATCH v3 3/4] usb: ohci-exynos: Add facility to use phy provided
 by the generic phy framework

On Mon, 28 Apr 2014, Vivek Gautam wrote:

> Add support to consume phy provided by Generic phy framework.
> Keeping the support for older usb-phy intact right now, in order
> to prevent any functionality break in absence of relevant
> device tree side change for ohci-exynos.
> Once we move to new phy in the device nodes for ohci, we can
> remove the support for older phys.
> 
> Signed-off-by: Vivek Gautam <gautam.vivek@...sung.com>
> Cc: Jingoo Han <jg1.han@...sung.com>
> Cc: Alan Stern <stern@...land.harvard.edu>
> ---

> +static int exynos_ohci_phy_enable(struct device *dev)
>  {
>  	struct usb_hcd *hcd = dev_get_drvdata(dev);
>  	struct exynos_ohci_hcd *exynos_ohci = to_exynos_ohci(hcd);
> +	int i;
> +	int ret = 0;
>  
> -	if (exynos_ohci->phy)
> -		usb_phy_init(exynos_ohci->phy);
> +	if (exynos_ohci->phy) {
> +		ret = usb_phy_init(exynos_ohci->phy);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	for (i = 0; ret == 0 && i < PHY_NUMBER; i++)
> +		if (exynos_ohci->phy_g[i])
> +			ret = phy_power_on(exynos_ohci->phy_g[i]);
> +	if (ret)
> +		for (i--; i >= 0; i--)
> +			if (exynos_ohci->phy_g[i])
> +				phy_power_off(exynos_ohci->phy_g[i]);

Do you want to call usb_phy_shutdown() at this point?

> +
> +	return ret;
>  }
>  
> -static void exynos_ohci_phy_disable(struct device *dev)
> +static int exynos_ohci_phy_disable(struct device *dev)
>  {
>  	struct usb_hcd *hcd = dev_get_drvdata(dev);
>  	struct exynos_ohci_hcd *exynos_ohci = to_exynos_ohci(hcd);
> +	int i;
> +	int ret = 0;
>  
>  	if (exynos_ohci->phy)
>  		usb_phy_shutdown(exynos_ohci->phy);
> +
> +	for (i = 0; i < PHY_NUMBER; i++)
> +		if (exynos_ohci->phy_g[i])
> +			ret = phy_power_off(exynos_ohci->phy_g[i]);
> +
> +	return ret;
>  }

This return value is practically meaningless.  It is the status from 
the last PHY only; any errors involving the other PHYs have been lost.

You may as well make this function return void.

> @@ -210,13 +302,18 @@ static int exynos_ohci_resume(struct device *dev)
>  {
>  	struct usb_hcd *hcd			= dev_get_drvdata(dev);
>  	struct exynos_ohci_hcd *exynos_ohci	= to_exynos_ohci(hcd);
> +	int ret;
>  
>  	clk_prepare_enable(exynos_ohci->clk);
>  
>  	if (exynos_ohci->otg)
>  		exynos_ohci->otg->set_host(exynos_ohci->otg, &hcd->self);
>  
> -	exynos_ohci_phy_enable(dev);
> +	ret = exynos_ohci_phy_enable(dev);
> +	if (ret) {
> +		dev_err(dev, "Failed to enable USB phy\n");

Do you want to call clk_disable_unprepare() here?

> +		return ret;
> +	}
>  
>  	ohci_resume(hcd, false);

Alan Stern

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