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

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Date:	Wed, 14 Aug 2013 10:21:58 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Linus Walleij <linus.walleij@...aro.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 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?

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