[PATCH v3 2/2] pinctrl: meson: restore non-sleeping GPIO access

Commit 28f240683871 ("pinctrl: meson: mark the GPIO controller as
sleeping") set gpio_chip.can_sleep = true to work around
gpio-shared-proxy holding a spinlock across a sleeping pinctrl config
path. That locking bug is now fixed in the shared-proxy itself ("gpio:
shared-proxy: always serialize with a sleeping mutex"), so the
controller-wide workaround is no longer needed; the meson GPIO
controller does not sleep.

meson_gpio_get/set/direction_* access MMIO through regmap. The
regmap_mmio bus uses fast I/O (spinlock) locking, so these value
callbacks do not contain sleeping operations. Since gpio_chip.can_sleep
describes the get/set value path, restore can_sleep = false.

Marking the controller sleeping also broke atomic value consumers such
as w1-gpio (1-Wire bitbang): w1_io.c runs its read time slot under
local_irq_save() and uses the non-cansleep gpiod_set_value() /
gpiod_get_value(), which with can_sleep=true trigger WARN_ON(can_sleep)
in gpiolib on every transferred bit (from w1_gpio_write_bit() /
w1_gpio_read_bit() via w1_reset_bus() and w1_search()). The printk and
stack dump inside the IRQs-off, microsecond-scale time slot destroy the
bit timing, so reset/presence detection and ROM search fail: the bus
master registers but w1_master_slave_count stays at 0 and no devices
are found. Verified on an Amlogic A113X board (DS18B20 on GPIOA_14):
with can_sleep restored to false the warnings are gone and the sensor
is detected and read again.

This must not be applied or backported without the shared-proxy locking
fix above; otherwise the original Khadas VIM3 splat returns on boards
that genuinely share a meson GPIO.

Fixes: 28f240683871 ("pinctrl: meson: mark the GPIO controller as sleeping")
Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Viacheslav Bocharov <[email protected]>
---
 drivers/pinctrl/meson/pinctrl-meson.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pinctrl/meson/pinctrl-meson.c b/drivers/pinctrl/meson/pinctrl-meson.c
index 4507dc8b5563..18295b15ecd9 100644
--- a/drivers/pinctrl/meson/pinctrl-meson.c
+++ b/drivers/pinctrl/meson/pinctrl-meson.c
@@ -619,7 +619,7 @@ static int meson_gpiolib_register(struct meson_pinctrl *pc)
 	pc->chip.set = meson_gpio_set;
 	pc->chip.base = -1;
 	pc->chip.ngpio = pc->data->num_pins;
-	pc->chip.can_sleep = true;
+	pc->chip.can_sleep = false;
 
 	ret = gpiochip_add_data(&pc->chip, pc);
 	if (ret) {
-- 
2.54.0


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