linux-kernel - Re: [PATCH 4/4] pinctrl: re-enable old state in case of error in pinctrl_select

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Date:	Thu, 28 Mar 2013 12:35:04 +0100
From:	Richard Genoud <richard.genoud@...il.com>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Stephen Warren <swarren@...dia.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] pinctrl: re-enable old state in case of error in pinctrl_select_state

2013/3/28 Stephen Warren <swarren@...dotorg.org>:
> On 03/25/2013 08:47 AM, Richard Genoud wrote:
>> If a new state is applied, the groups configured in the old state but
>> not in the new state are disabled.
>> If something goes wrong and the new state can't be applied, we have to
>> re-enable those groups.
>
> What is the use-case for this? I wonder if it isn't better to simply
> undo the partial selection of the new state (as patch 3/4 attempts to
> do) and then leave p->state==NULL, indicating that no state is actively
> selected. IIRC, this would be the same as right after the initial
> pinctrl_select().
>
> I wonder if it's likely that attempting to re-apply the old state would
> actually work, given that applying something just failed.
>
> Finally, this recovery code doesn't:
>
> a) Process anything except MUX_GROUP; any pin config settings in the old
> state aren't restored.
>
> b) (I think) Apply any mux settings that don't involve groups that are
> referenced by both the old and new states; given that patch 3/4 attempts
> to undo everything in the failed application of the new state, I think
> this "re-apply the old state" code should simple run through everything
> in the old state any apply it unconditionally.
Well, I'm not comfortable enough with this code to argue on that...

> c) Set p->state = oldstate, so it's left at NULL, which would confuse
> any future pinctrl_select().
Arrrggg !
I forgot it !
I'll send a fix on that


-- 
for me, ck means con kolivas and not calvin klein... does it mean I'm a geek ?
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