linux-kernel - Re: [PATCH-next 10/20] gpio: gpio-omap: simplify set

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Message-ID: <CACRpkdYCiPRPM7evyZsL2jvsfiAYZ36fL1PRjoG7a0jvduqpwQ@mail.gmail.com>
Date:   Wed, 12 Jun 2019 10:51:49 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Grygorii Strashko <grygorii.strashko@...com>
Cc:     Russell King <rmk@....linux.org.uk>,
        Tony Lindgren <tony@...mide.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Linux-OMAP <linux-omap@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Russell King <rmk+kernel@...linux.org.uk>
Subject: Re: [PATCH-next 10/20] gpio: gpio-omap: simplify set_multiple()

On Mon, Jun 10, 2019 at 7:12 PM Grygorii Strashko
<grygorii.strashko@...com> wrote:

> From: Russell King <rmk+kernel@...linux.org.uk>
>
> One of the reasons for set_multiple() to exist is to allow multiple
> GPIOs on the same chip to be changed simultaneously - see commit
> 5f42424354f5 ("gpiolib: allow simultaneous setting of multiple GPIO
> outputs"):
>
>  - Simultaneous glitch-free setting of multiple pins on any kind of
>    parallel bus attached to GPIOs provided they all reside on the
>    same chip and bank.
>
> In order for this to work, we should not use the atomic set/clear
> registers, but instead read-modify-write the dataout register.  We
> already take the spinlock to ensure that happens atomically, so
> move the code into the set_multiple() function and kill the two
> helper functions.
>
> Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>

Patch applied.

Yours,
Linus Walleij