linux-kernel - Re: [PATCH v2 3/4] gpio: aspeed: Add debounce support

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Date:   Mon, 24 Apr 2017 14:50:35 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Andrew Jeffery <andrew@...id.au>
Cc:     Rob Herring <robh+dt@...nel.org>, Joel Stanley <joel@....id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>
Subject: Re: [PATCH v2 3/4] gpio: aspeed: Add debounce support

On Fri, Apr 7, 2017 at 2:59 PM, Andrew Jeffery <andrew@...id.au> wrote:

> Each GPIO in the Aspeed GPIO controller can choose one of four input
> debounce states: to disable debouncing for an input, or select from one
> of three programmable debounce timer values. Each GPIO in a
> four-bank-set is assigned one bit in each of two debounce configuration
> registers dedicated to the set, and selects a debounce state by
> configuring the two bits to select one of the four options.
>
> The limitation on debounce timer values is managed by mapping offsets
> onto a configured timer value and keeping count of the number of users
> a timer has. Timer values are configured on a first-come-first-served
> basis.
>
> A small twist in the hardware design is that the debounce configuration
> register numbering is reversed with respect to the binary representation
> of the debounce timer of interest (i.e. debounce register 1 represents
> bit 1, and debounce register 2 represents bit 0 of the timer numbering).
>
> Tested on an AST2500EVB with additional inspection under QEMU's
> romulus-bmc machine.
>
> Signed-off-by: Andrew Jeffery <andrew@...id.au>

Patch applied.

Yours,
Linus Walleij