[PATCH v4 0/2] pinctrl: stm32: fix hwspinlock timeout and EXTI mux locking

[Ju Nan]

This series fixes two problems around the hwspinlock-protected EXTI mux
and pin configuration accesses in the STM32 pinctrl driver.

Patch 1 fixes the timeout passed to hwspin_lock_timeout_in_atomic().
The value was written as 1000 microseconds, but the argument is in
milliseconds, so the driver could busy-wait for up to one second with
interrupts disabled instead of the intended one millisecond. It is a
standalone fix and can be applied on its own.

Patch 2 moves the EXTI mux programming from the irq domain .activate
callback to .alloc. .activate runs under the raw desc->lock, while the
mux is written through a syscon regmap protected by a spinlock_t, which
lockdep reports as an invalid wait context and which is a real bug on
PREEMPT_RT. This was originally reported by Uwe Kleine-König in 2022.
.alloc runs in sleepable context and already reserves the mux line, so
the write now happens in the same irqmux_lock section as the
reservation. While at it, the reservation is released when the
hwspinlock cannot be taken.

---
Changes in v4:

- make the two patches a series to resolve the dependency issue
- reproduce the bug fixed by patch 2 on a modified version of
  STM32MP157-DK board with kernel version 7.1.13
- check the concurrent-requester case raised by Antonio in v3: the
  second bank is rejected in .alloc under irqmux_lock (details in
  patch 2)

v3: https://lore.kernel.org/all/20260804141402.86911-2-junan76@163.com/
v2: https://lore.kernel.org/all/20260804032227.35017-3-junan76@163.com/
v1: https://lore.kernel.org/all/20260803061718.43210-1-junan76@163.com/

Ju Nan (2):
  pinctrl: stm32: Fix the unit of the hwspinlock timeout
  pinctrl: stm32: program the EXTI mux from .alloc instead of .activate

 drivers/pinctrl/stm32/pinctrl-stm32.c | 60 ++++++++++++---------------
 1 file changed, 26 insertions(+), 34 deletions(-)

-- 
2.56.0