From: Nikita Maslo <nikitamalco203@gmail.com>
To: Bartosz Golaszewski <brgl@kernel.org>, Linus Walleij <linusw@kernel.org>
Cc: Nikita Maslo <nikitamalco203@gmail.com>,
linux-gpio@vger.kernel.org, linux-amlogic@lists.infradead.org
Subject: Broken bitbang 1-wire on Amlogic after kernel update
Date: Fri, 15 May 2026 17:38:00 +0300 [thread overview]
Message-ID: <20260515143801.2132974-1-nikitamalco203@gmail.com> (raw)
Hi,
I was running linux-6.12.67 on a hardkernel odroid-c2 (Amlogic S905) Amlogic board with DS18B20 on
w1-gpio (1-Wire bitbang), everything worked fine. After updating the
kernel, 1-wire stopped working the DS18B20 fails to enumerate or
reads back the broken-bus, and dmesg
gets flooded with WARNINGs from gpiod_set_value/gpiod_get_value
called from w1_gpio_write_bit/w1_gpio_read_bit.
Hardware: Hardkernel ODROID-C2 (Amlogic S905).
Kernel: linux-6.18.15 (also reproduces on linux-6.12.69; last
known-good for me was linux-6.12.67).
Device tree fragment used:
/ {
onewire {
compatible = "w1-gpio";
gpios = <&gpio GPIOX_17 GPIO_ACTIVE_HIGH>;
};
};
dmesg, captured on ODROID-C2 / linux-6.18.15:
[ 59.102855] ------------[ cut here ]------------
[ 59.102891] WARNING: CPU: 0 PID: 1145 at drivers/gpio/gpiolib.c:3880 gpiod_set_value+0x78/0x88
[ 59.103569] CPU: 0 UID: 0 PID: 1145 Comm: w1_bus_master1 Tainted: G WC 6.18.15-current-meson64 #8 PREEMPT
[ 59.103618] Hardware name: Hardkernel ODROID-C2 (DT)
[ 59.103658] pc : gpiod_set_value+0x78/0x88
[ 59.103687] lr : w1_gpio_write_bit+0x20/0x38 [w1_gpio]
[ 59.104161] Call trace:
[ 59.104175] gpiod_set_value+0x78/0x88 (P)
[ 59.104210] w1_gpio_write_bit+0x20/0x38 [w1_gpio]
[ 59.104238] w1_reset_bus+0x84/0xe0 [wire]
[ 59.104272] w1_search+0x88/0x2a0 [wire]
[ 59.104304] w1_search_devices+0x54/0x90 [wire]
[ 59.104336] w1_search_process_cb+0x84/0x170 [wire]
[ 59.104368] w1_process+0x1c0/0x238 [wire]
[ 59.104400] kthread+0x14c/0x218
[ 59.104432] ret_from_fork+0x10/0x20
[ 59.104464] ---[ end trace 0000000000000000 ]---
A symmetric WARN at gpiolib.c:3501 fires from gpiod_get_value via
w1_gpio_read_bit on every read slot.
After a little researching, the suspect commit looks like:
28f240683871 ("pinctrl: meson: mark the GPIO controller as sleeping")
I also tested bitbang i2c-gpio on the same hardware after the update,
it seems to keep working.
reply other threads:[~2026-05-15 14:38 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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