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

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Message-ID: <CACRpkdZbZF6pHdfgrFqf-Uuoipv=vmK7Y4CCqPjj21QYN-zNfA@mail.gmail.com>
Date:	Wed, 14 Aug 2013 17:54:32 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Sonic Zhang <sonic.adi@...il.com>
Cc:	Grant Likely <grant.likely@...aro.org>,
	Stephen Warren <swarren@...dotorg.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 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.

Yours,
Linus Walleij
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