linux-kernel - Re: [PATCH v2 2/2] i2c: core: support recovery for single-ended GPIOs

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Message-ID: <CAD++jLnk_5KG_q1aCtpOrTCbhtK-FxXH6BhPFSwukyt2F4uxmQ@mail.gmail.com>
Date: Tue, 27 Jan 2026 10:47:03 +0100
From: Linus Walleij <linusw@...nel.org>
To: Jie Li <lj29312931@...il.com>
Cc: wsa@...nel.org, linus.walleij@...aro.org, linux-i2c@...r.kernel.org, 
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Jie Li <jie.i.li@...ia.com>
Subject: Re: [PATCH v2 2/2] i2c: core: support recovery for single-ended GPIOs

On Sun, Jan 25, 2026 at 8:51 PM Jie Li <lj29312931@...il.com> wrote:

> Currently, i2c_init_recovery() only assigns the set_sda/set_scl
> hooks if gpiod_get_direction() returns 0 (output).
>
> This logic fails on certain SoC controllers where open-drain lines
> in a high-impedance state are physically reported as inputs. This
> leads to a "deadlock" where the I2C core refuses to assign the
> recovery hooks because it incorrectly assumes the pins are
> input-only, even though they are fully capable of driving the bus
> low for recovery.
>
> Update the recovery initialization to use the new
> gpiod_is_single_ended() helper. If a GPIO is configured as
> open-drain or open-source in the firmware, it is safe to assume
> it can be used for bus recovery, even if the current hardware
> direction is reported as input.
>
> Signed-off-by: Jie Li <jie.i.li@...ia.com>

This looks good!
Reviewed-by: Linus Walleij <linusw@...nel.org>

Yours,
Linus Walleij