From: Wolfram Sang <wsa+renesas@sang-engineering.com>
To: Bartosz Golaszewski <brgl@kernel.org>
Cc: markus.stockhausen@gmx.de, andi.shyti@kernel.org,
linux-i2c@vger.kernel.org
Subject: Re: AW: [PATCH 1/2] dt-bindings: i2c: Add i2c-shared-gpio
Date: Mon, 11 May 2026 17:39:08 +0200 [thread overview]
Message-ID: <agH4HKEQ0BGK4fbt@ninjato> (raw)
In-Reply-To: <CAMRc=MfN=jNiPRp_fS9T-39s7c366ak4MC6DWGFreonCZM92FA@mail.gmail.com>
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> >> @Bart: is it possible to share a GPIO so that multiple i2c-gpio
> >> instances can use the same GPIO as SCL? Use case is explained in the
> >> cover letter[2].
> >
>
> The way it works is with a kind of a voting system. As long as there's at
> least one user that votes for the GPIO to be "high", it stays high. Is this
> behavior fine for the recovery use-case?
Ouch, I guess this will not work then. SCL is high in its idle state.
So, all busses except the active one will request high :(
I guess Markus would need some kind of locking for the shared SCL-GPIO
anyhow. Like bus Y has to wait until bus X has finished SCL toggling for
its transfer. That's how I understand it.
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next prev parent reply other threads:[~2026-05-11 15:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-07 18:17 [PATCH 0/2] i2c: Add i2c-shared-gpio driver Markus Stockhausen
2026-05-07 18:17 ` [PATCH 1/2] dt-bindings: i2c: Add i2c-shared-gpio Markus Stockhausen
2026-05-07 19:30 ` Rob Herring (Arm)
2026-05-08 13:18 ` Rob Herring
2026-05-08 14:43 ` AW: " markus.stockhausen
2026-05-09 17:38 ` Wolfram Sang
2026-05-09 20:41 ` AW: " markus.stockhausen
2026-05-11 12:43 ` Bartosz Golaszewski
2026-05-11 15:39 ` Wolfram Sang [this message]
2026-05-11 16:08 ` Bartosz Golaszewski
2026-05-13 16:21 ` Rob Herring
2026-05-13 17:19 ` AW: " markus.stockhausen
2026-05-13 21:34 ` 'Wolfram Sang'
2026-05-09 11:16 ` markus.stockhausen
2026-05-07 18:17 ` [PATCH 2/2] i2c: shared-gpio: Add driver for gpio based busses with shared SCL Markus Stockhausen
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