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

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Message-ID: <CACRpkdZMCO9Cw=SMk4cq8k0+eqYrK=kKsjfAHut1=PXjxS_6jA@mail.gmail.com>
Date:	Wed, 7 Aug 2013 18:23:22 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Sonic Zhang <sonic.adi@...il.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Axel Lin <axel.lin@...ics.com>
Cc:	Grant Likely <grant.likely@...aro.org>,
	Steven Miao <realmz6@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	buildroot-devel@...ckfin.uclinux.org,
	adi-buildroot-devel@...ts.sourceforge.net,
	Sonic Zhang <sonic.zhang@...log.com>
Subject: Re: [PATCH] pinctrl: pinmux: Don't free pins requested by other devices

On Wed, Jul 17, 2013 at 7:31 AM, Sonic Zhang <sonic.adi@...il.com> wrote:

I'd like Stephen and Axel to have a look at this as well...

> From: Sonic Zhang <sonic.zhang@...log.com>
>
> in pinmux_disable_setting after current device fails to request
> the same pins.
>
> Signed-off-by: Sonic Zhang <sonic.zhang@...log.com>

I don't quite understand the patch. Can you provide more context?

> diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
> index 88cc509..9ebcf3b 100644
> --- a/drivers/pinctrl/pinmux.c
> +++ b/drivers/pinctrl/pinmux.c
> @@ -482,13 +482,14 @@ void pinmux_disable_setting(struct pinctrl_setting const *setting)
>                                  pins[i]);
>                         continue;
>                 }
> +               /* And release the pins */
> +               if (desc->mux_usecount &&
> +                       !strcmp(desc->mux_owner, setting->dev_name))
> +                       pin_free(pctldev, pins[i], NULL);
> +
>                 desc->mux_setting = NULL;
>         }
>
> -       /* And release the pins */
> -       for (i = 0; i < num_pins; i++)
> -               pin_free(pctldev, pins[i], NULL);
> -

For pinmux_disable_setting() to inspect desc->mux_usecount seems
assymetric. This is something pin_free() should do, shouldn't it?

Should not this codepath be kept and a change made inside pin_free()
for the check above instead?

Yours,
Linus Walleij
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