linux-kernel - Re: [PATCHv4 08/12] usb: dwc2: gadget: Do not fail probe if there isn't a clock node

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Message-id: <3825627.ZuOPzBNWiB@amdc1032>
Date:	Fri, 12 Sep 2014 18:28:58 +0200
From:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:	dinguyen@...nsource.altera.com
Cc:	paulz@...opsys.com, gregkh@...uxfoundation.org, balbi@...com,
	dinh.linux@...il.com, swarren@...dotorg.org, matthijs@...in.nl,
	r.baldyga@...sung.com, jg1.han@...sung.com,
	sachin.kamat@...aro.org, ben-linux@...ff.org,
	dianders@...omium.org, kever.yang@...k-chips.com,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv4 08/12] usb: dwc2: gadget: Do not fail probe if there
 isn't a clock node


[ added linux-kernel ML to cc: ]

Hi,

On Tuesday, August 26, 2014 11:19:59 AM dinguyen@...nsource.altera.com wrote:
> From: Dinh Nguyen <dinguyen@...nsource.altera.com>
> 
> Since the dwc2 hcd driver is currently not looking for a clock node during
> init, we should not completely fail if there isn't a clock provided.
> Add a check for a valid clock before calling clock functions.

This doesn't look correct at least for the case when we are really missing
the clock and USB_DWC2_PERIPHERAL=y (moreover it just looks wrong to access
gadget functionalities when clock is disabled). It seems that it would be
better to just disable gadget functionality on dwc2_gadget_init() failure
in hcd and not call gadget functions later from hcd if gadget functionality
is disabled.

> Signed-off-by: Dinh Nguyen <dinguyen@...nsource.altera.com>
> Acked-by: Paul Zimmerman <paulz@...opsys.com>
> ---
>  drivers/usb/dwc2/gadget.c | 36 ++++++++++++++++++++++--------------
>  1 file changed, 22 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> index a1c93bf..aab1b45 100644
> --- a/drivers/usb/dwc2/gadget.c
> +++ b/drivers/usb/dwc2/gadget.c
> @@ -2852,7 +2852,8 @@ static int s3c_hsotg_udc_start(struct usb_gadget *gadget,
>  	hsotg->gadget.dev.of_node = hsotg->dev->of_node;
>  	hsotg->gadget.speed = USB_SPEED_UNKNOWN;
>  
> -	clk_enable(hsotg->clk);
> +	if (!IS_ERR(hsotg->clk))
> +		clk_enable(hsotg->clk);
>  
>  	ret = regulator_bulk_enable(ARRAY_SIZE(hsotg->supplies),
>  				    hsotg->supplies);
> @@ -2903,7 +2904,8 @@ static int s3c_hsotg_udc_stop(struct usb_gadget *gadget,
>  	regulator_bulk_disable(ARRAY_SIZE(hsotg->supplies),
>  				hsotg->supplies);
>  
> -	clk_disable(hsotg->clk);
> +	if (!IS_ERR(hsotg->clk))
> +		clk_disable(hsotg->clk);
>  
>  	return 0;
>  }
> @@ -2936,10 +2938,12 @@ static int s3c_hsotg_pullup(struct usb_gadget *gadget, int is_on)
>  	spin_lock_irqsave(&hsotg->lock, flags);
>  	if (is_on) {
>  		s3c_hsotg_phy_enable(hsotg);
> -		clk_enable(hsotg->clk);
> +		if (!IS_ERR(hsotg->clk))
> +			clk_enable(hsotg->clk);
>  		s3c_hsotg_core_init(hsotg);
>  	} else {
> -		clk_disable(hsotg->clk);
> +		if (!IS_ERR(hsotg->clk))
> +			clk_disable(hsotg->clk);
>  		s3c_hsotg_phy_disable(hsotg);
>  	}
>  
> @@ -3410,16 +3414,15 @@ int dwc2_gadget_init(struct dwc2_hsotg *hsotg, int irq)
>  	}
>  
>  	hsotg->clk = devm_clk_get(dev, "otg");
> -	if (IS_ERR(hsotg->clk)) {
> -		dev_err(dev, "cannot get otg clock\n");
> -		return PTR_ERR(hsotg->clk);
> -	}
> +	if (IS_ERR(hsotg->clk))
> +		dev_warn(dev, "cannot get otg clock\n");
>  
>  	hsotg->gadget.max_speed = USB_SPEED_HIGH;
>  	hsotg->gadget.ops = &s3c_hsotg_gadget_ops;
>  	hsotg->gadget.name = dev_name(dev);
>  
> -	clk_prepare_enable(hsotg->clk);
> +	if (!IS_ERR(hsotg->clk))
> +		clk_prepare_enable(hsotg->clk);
>  
>  	/* regulators */
>  
> @@ -3452,7 +3455,8 @@ int dwc2_gadget_init(struct dwc2_hsotg *hsotg, int irq)
>  			dev_name(dev), hsotg);
>  	if (ret < 0) {
>  		s3c_hsotg_phy_disable(hsotg);
> -		clk_disable_unprepare(hsotg->clk);
> +		if (!IS_ERR(hsotg->clk))
> +			clk_disable_unprepare(hsotg->clk);
>  		regulator_bulk_disable(ARRAY_SIZE(hsotg->supplies),
>  				       hsotg->supplies);
>  		dev_err(dev, "cannot claim IRQ\n");
> @@ -3521,7 +3525,8 @@ err_ep_mem:
>  err_supplies:
>  	s3c_hsotg_phy_disable(hsotg);
>  err_clk:
> -	clk_disable_unprepare(hsotg->clk);
> +	if (!IS_ERR(hsotg->clk))
> +		clk_disable_unprepare(hsotg->clk);
>  
>  	return ret;
>  }
> @@ -3541,7 +3546,8 @@ int s3c_hsotg_remove(struct dwc2_hsotg *hsotg)
>  		usb_gadget_unregister_driver(hsotg->driver);
>  	}
>  
> -	clk_disable_unprepare(hsotg->clk);
> +	if (!IS_ERR(hsotg->clk))
> +		clk_disable_unprepare(hsotg->clk);
>  
>  	return 0;
>  }
> @@ -3568,7 +3574,8 @@ static int s3c_hsotg_suspend(struct dwc2_hsotg *hsotg)
>  
>  		ret = regulator_bulk_disable(ARRAY_SIZE(hsotg->supplies),
>  					     hsotg->supplies);
> -		clk_disable(hsotg->clk);
> +		if (!IS_ERR(hsotg->clk))
> +			clk_disable(hsotg->clk);
>  	}
>  
>  	return ret;
> @@ -3583,7 +3590,8 @@ static int s3c_hsotg_resume(struct dwc2_hsotg *hsotg)
>  		dev_info(hsotg->dev, "resuming usb gadget %s\n",
>  			 hsotg->driver->driver.name);
>  
> -		clk_enable(hsotg->clk);
> +		if (!IS_ERR(hsotg->clk))
> +			clk_enable(hsotg->clk);
>  		ret = regulator_bulk_enable(ARRAY_SIZE(hsotg->supplies),
>  					   hsotg->supplies);
>  	}

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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