linux-kernel - Re: [PATCH] pinctrl: add params in disable

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Date:	Fri, 16 May 2014 13:53:11 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Linus Walleij <linus.walleij@...aro.org>, FanWu <fwu@...vell.com>,
	ext Tony Lindgren <tony@...mide.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Stephen Warren <swarren@...dia.com>,
	Chao Xie <cxie4@...vell.com>, ylmao@...vell.com,
	njiang1@...vell.com, tianxf@...vell.com, fswu@...vell.com
Subject: Re: [PATCH] pinctrl: add params in disable_setting for different
 usage

On 05/16/2014 10:21 AM, Linus Walleij wrote:
> On Wed, May 14, 2014 at 4:01 AM,  <fwu@...vell.com> wrote:
> 
>> From: Fan Wu <fwu@...vell.com>
>>
>> The patch added params in disable_setting to differ the two possible usage,
>> 1.Only want to disable the pin setting in SW aspect, param can be set to "0"
>> 2.Want to disable the pin setting in both HW and SW aspect, param can be set to "1";
>>
>> The reason why to do this is that:
>> To avoid duplicated enable_setting operation without disabling operation which will
>> let Pin's desc->mux_usecount keep being added.
>>
>> In the following case, the issue can be reproduced:
>> 1)There is a driver need to switch Pin state dynamicly, E.g. b/t "sleep" and
>> "default" state
>> 2)The Pin setting configuration in the two state is same, like the following one:
>> component a {
>>         pinctrl-names = "default", "sleep";
>>         pinctrl-0 = <&a_grp_setting &c_grp_setting>;
>>         pinctrl-1 = <&b_grp_setting &c_grp_setting>;
>> }
>> The "c_grp_setting" config node is totaly same, maybe like following one:
> 
> Hm this is a quite interesting thing if we can get it in place, but
> I need Stephen's consent, also Tony should have a look at this as
> I know he's had the same problem as you in pinctrl-single.

I only briefly looked at the patch, but it probably solves/hides the
immediate problem.

However, rather than doing this, why not just remove
pinmux_disable_setting() completely. It doesn't make sense to "disable a
mux selection" (some value is always selected in the mux register field)
any more than it does to "disable a drive strength selection". We don't
have a pinconf_disable_setting(), and couldn't really add one if we
wanted. For consistency, let's just remove pinmux_disable_setting(). Do
you agree?
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