linux-kernel - Re: [PATCH 2/2] drivers/gpio/gpio-adp5588.c: switch to events system

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Date:   Fri, 8 Feb 2019 14:43:00 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Nikolaus Voss <nv@...n.de>
Cc:     Michael Hennerich <michael.hennerich@...log.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Nikolaus Voss <nikolaus.voss@...wensteinmedical.de>
Subject: Re: [PATCH 2/2] drivers/gpio/gpio-adp5588.c: switch to events system

On Tue, Feb 5, 2019 at 4:17 PM Nikolaus Voss <nv@...n.de> wrote:

> Interupts were generated using GPIN interrupts of
> ADP5588. These interrupts have two important limitations:
> 1. Interrupts can only be generated for either rising or
>    falling edges but not both.
> 2. Interrupts are reasserted as long as the interrupt condition
>    persists (i.e. high or low level on that GPIN). This generates
>    lots of interrupts unless the event is very short.
>
> To overcome this, ADP5588 provides an event system which queues
> up to 10 events in a buffer. GPIN events are queued whenever the
> GPIN is asserted or deasserted. This makes it possible to support
> generating GPIN interrupts for both edges and to generate only one
> interrupt per state change.
> Thus it is possible to chain the gpio-keys driver for some GPIOs.
>
> Signed-off-by: Nikolaus Voss <nikolaus.voss@...wensteinmedical.de>

Patch applied with Michael's ACK.

Yours,
Linus Walleij