linux-kernel - Re: [PATCH v3] pinctrl: pinmux: Don't free pins requested by other devices in pinmux_disable

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Date:	Tue, 13 Aug 2013 09:46:24 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Sonic Zhang <sonic.adi@...il.com>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	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 v3] pinctrl: pinmux: Don't free pins requested by other
 devices in pinmux_disable_setting.

On 08/12/2013 10:54 PM, Sonic Zhang 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.

> diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c

> @@ -480,15 +480,17 @@ void pinmux_disable_setting(struct pinctrl_setting const *setting)
>  			dev_warn(pctldev->dev,
>  				 "could not get pin desc for pin %d\n",
>  				 pins[i]);
> +			/* And release the pin */
> +			pin_free(pctldev, pins[i], NULL);

This change doesn't seem useful. The 2 lines right above the patch
context are:

		desc = pin_desc_get(pctldev, pins[i]);
                if (desc == NULL) {

... and the first thing pin_free() does it call pin_desc_get() again.
So, pin_free() is simply going to fail and print another error.

The rest of the patch looks good.

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