From: Rob Herring <robh@kernel.org>
To: Tapio Reijonen <tapio.reijonen@vaisala.com>
Cc: Peter Rosin <peda@lysator.liu.se>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/2] dt-bindings: mux: gpio-mux: Add enable-gpios
Date: Tue, 8 Sep 2026 10:56:32 -0500 [thread overview]
Message-ID: <20260908155632.GA3264563-robh@kernel.org> (raw)
In-Reply-To: <20260904-add-external-mux-enable-gpio-v3-1-1b868e669e43@vaisala.com>
On Fri, Sep 04, 2026 at 06:17:36AM +0000, Tapio Reijonen wrote:
> Analog multiplexers have an enable input besides the address inputs. On a
> 74HC4051 it is the E input: with E high, all eight switches are in the
> high-impedance off state, independent of S0 to S2. A 74HC4067 works the
> same way with four address inputs.
>
> Two things need that input. The mux-controller binding describes an idle
> state of disconnect, which a gpio-mux cannot reach today because the
> address inputs always select a channel. And the address inputs are plain
> gpios that may live on different gpio controllers, so they are not
> updated in one go and the mux passes through the intermediate addresses
> on every channel change unless it is disabled meanwhile.
>
> Add enable-gpios to describe the enable input, and require it for an idle
> state of disconnect.
>
> Signed-off-by: Tapio Reijonen <tapio.reijonen@vaisala.com>
Missing Conor's ack.
next prev parent reply other threads:[~2026-09-08 15:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-04 6:17 [PATCH v3 0/2] mux: gpio: Add optional enable gpio Tapio Reijonen
2026-09-04 6:17 ` [PATCH v3 1/2] dt-bindings: mux: gpio-mux: Add enable-gpios Tapio Reijonen
2026-09-08 15:56 ` Rob Herring [this message]
2026-09-04 6:17 ` [PATCH v3 2/2] mux: gpio: Add optional enable gpio Tapio Reijonen
2026-09-04 6:28 ` sashiko-bot
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