linux-kernel - Re: [PATCH] usb: phy: samsung-usb2: Toggle HSIC GPIO from device tree

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Message-ID: <CAHbNUh06Rxd9JRieeXCydB_JwiUOrUXADL6nUGZxONQJmz2-CQ@mail.gmail.com>
Date:	Wed, 28 Aug 2013 09:25:22 +0530
From:	Tushar Behera <tushar.behera@...aro.org>
To:	balbi@...com
Cc:	Julius Werner <jwerner@...omium.org>,
	LKML <linux-kernel@...r.kernel.org>, linux-usb@...r.kernel.org,
	devicetree-discuss@...ts.ozlabs.org,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	Vivek Gautam <gautam.vivek@...sung.com>,
	Praveen Paneri <p.paneri@...sung.com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Doug Anderson <dianders@...omium.org>,
	Olof Johansson <olofj@...omium.org>,
	Vincent Palatin <vpalatin@...omium.org>
Subject: Re: [PATCH] usb: phy: samsung-usb2: Toggle HSIC GPIO from device tree

On 28 August 2013 00:14, Felipe Balbi <balbi@...com> wrote:
> On Tue, Aug 13, 2013 at 02:11:27PM +0530, Tushar Behera wrote:
>> On 12 July 2013 12:27, Felipe Balbi <balbi@...com> wrote:
>> > Hi,
>> >
>> > On Wed, Jul 10, 2013 at 10:42:27AM -0700, Julius Werner wrote:
>> >> Hi Felipe,
>> >>
>> >> This is intended to pull down a reset signal line, not to switch power
>> >> to the device. I could implement that with the regulator framework
>> >> too, but I think that would just be confusing and harder to understand
>> >> without providing any benefit. It's really just a plain old GPIO.
>> >
>> > alright, in that case how about using drivers/reset/ ?
>> >
>>
>> IIUC, reset-gpio driver only provides APIs for reset controls (reset,
>> assert, deassert). We still need to find out the location from where
>> we would be calling the reset function.
>
> that's fair, but at least you reuse a bunch of boilerplate code to claim
> the GPIO, set proper direction and value. No need to duplicate that in
> your driver.
>

SMSC3503 driver code was recently updated by Mark Brown [1] which
allows the device to work even if it is not connected to I2C bus. The
timing is still an issue though [2]. With this USB works on
linux-next, but surely that [2] is not the solution.

[1] http://comments.gmane.org/gmane.linux.usb.general/92061
[2] https://lkml.org/lkml/2013/8/14/814
-- 
Tushar Behera
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