linux-kernel - Re: [PATCH v4] pinctrl: pinmux: Don't free pins requested by other devices in pinmux_disable

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Message-ID: <CACRpkdbJ4TYQ+X65166enY54w=4OjDrtEc-t4MzWYvBy=jt_jA@mail.gmail.com>
Date:	Wed, 14 Aug 2013 18:27:58 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Sonic Zhang <sonic.adi@...il.com>,
	Grant Likely <grant.likely@...aro.org>,
	LKML <linux-kernel@...r.kernel.org>,
	adi-buildroot-devel@...ts.sourceforge.net,
	Sonic Zhang <sonic.zhang@...log.com>
Subject: Re: [PATCH v4] pinctrl: pinmux: Don't free pins requested by other
 devices in pinmux_disable_setting.

On Wed, Aug 14, 2013 at 6:21 PM, Stephen Warren <swarren@...dotorg.org> wrote:
> On 08/14/2013 09:54 AM, Linus Walleij wrote:
>> On Wed, Aug 14, 2013 at 7:26 AM, Sonic Zhang <sonic.adi@...il.com> wrote:
>>
>>> From: Sonic Zhang <sonic.zhang@...log.com>
>>>
>>> One peripheral may share part of its pins with the 2nd
>>> peripheral and the other pins with the 3rd. If it requests all pins
>>> when part of them has already be requested and owned by the 2nd
>>> peripheral, this request fails and pinmux_disable_setting() is called.
>>> The pinmux_disable_setting() frees all pins of the first peripheral
>>> without checking if the pin is owned by itself or the 2nd, which
>>> results in the malfunction of the 2nd peripheral driver.
>>>
>>> Signed-off-by: Sonic Zhang <sonic.zhang@...log.com>
>>
>> Hm it makes some sense so patch applied.
>>
>> That said I think we currently have drivers where a pin group
>> mapped to a certain function in a certain setting  *usually*
>> don't overlap with pins in another group used with another
>> function, and having it so seems racy, i.e. it will be some
>> first-come-first-serve effect.
>>
>> I will add a warning print.
>
> Surely there's a warning print already when the enable_setting() fails,
> so we don't need to do any more warning prints when the free_setting()
> cleans up after that?

Now I'm confused ... I added debug prints to pinmux_disable_setting()
which is where the patch hits? free_setting() is just an empty function
body still.

Yours,
Linus Walleij
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