From mboxrd@z Thu Jan  1 00:00:00 1970
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
Date: Wed, 9 Oct 2013 13:44:25 +0100
Subject: [PATCH] pinctrl: phandle entries will be applied sequentially
In-Reply-To: <CACRpkdazPK6SNg9PdWCrjB8nwho1rCueumJWAN=STXdN1zNnMA@mail.gmail.com>
References: <1381297324-19006-1-git-send-email-shawn.guo@linaro.org>
 <CACRpkdazPK6SNg9PdWCrjB8nwho1rCueumJWAN=STXdN1zNnMA@mail.gmail.com>
Message-ID: <20131009124425.GG25034@n2100.arm.linux.org.uk>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Wed, Oct 09, 2013 at 02:40:49PM +0200, Linus Walleij wrote:
> NAK this this a Linux kernel implementation detail. Sherman Yin
> fixed this up so the drivers does not have to imply any sequence
> semantic for this.
> 
> Study commit 03b054e9696c3cbd3d5905ec96da15acd0a2fe8d
> "pinctrl: Pass all configs to driver on pin_config_set()"
> 
> It is perfectly legal for a driver to accumulate the settings into
> e.g. a single register write if it can, e.g.:
> 
> u32 val = 0;
> 
> for (i = 0; i < num_configs; i++) {
>   switch() {
>   FOO:
>      val |= 1;
>      break;
>    BAR:
>      val |= 2:
>      break;
>    BAZ:
>      val |=4;
>      break;
> };
> 
> writel(val, base+pinreg);
> 
> I.e. the driver may choose to apply configs sequentially, but that is
> not at all necessary.

So, just to be clear, what you're saying is that specifying two settings
in a pinctrl declaration which provide different values results in
undefined behaviour?