linux-kernel - Re: [PATCH] USB: ehci-s5p: Fix phy reset

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Date:	Wed, 13 Mar 2013 18:45:52 +0100
From:	Alexander Graf <agraf@...e.de>
To:	Doug Anderson <dianders@...omium.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-usb@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	dmueller@...e.de, Vivek Gautam <gautam.vivek@...sung.com>,
	Jingoo Han <jg1.han@...sung.com>,
	Alan Stern <stern@...land.harvard.edu>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] USB: ehci-s5p: Fix phy reset


On 13.03.2013, at 18:28, Doug Anderson wrote:

> Alexander,
> 
> On Tue, Mar 12, 2013 at 6:09 PM, Alexander Graf <agraf@...e.de> wrote:
>> -       err = gpio_request_one(gpio, GPIOF_OUT_INIT_HIGH, "ehci_vbus_gpio");
>> -       if (err)
>> +       /* reset pulls the line down, then up again */
>> +       err = gpio_request_one(gpio, GPIOF_OUT_INIT_LOW, "ehci_vbus_gpio");
>> +       if (err) {
>>                dev_err(&pdev->dev, "can't request ehci vbus gpio %d", gpio);
>> +               return;
>> +       }
>> +       mdelay(1);
>> +       __gpio_set_value(gpio, 1);
>> +       gpio_free(gpio);
> 
> Freeing the gpio is a little on the iffy side since you actually care
> about keeping the value.  Perhaps you can change this to
> devm_gpio_request_one() and avoid the free?  I was about to submit a
> patch to do just that (since otherwise you run into trouble if you
> ever defer the probe) but then ran across your patch.

I could also just return it when the function exits and only free it when we exit the probe function with a negative value. The reason I put it in here was that on probe deferral, the pin simply gets blocked.

However, I could probably also just completely take the gpio_free() out of this patch and resubmit, as it should be pretty much unrelated. Then you can patch it properly.


Alex

> 
> Thanks!
> 
> -Doug

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