[PATCH 5.10.y 2/2] irqchip/stm32mp-exti: Fix the unit of the hwspinlock timeout

[Sasha Levin <sashal@kernel.org>]

From: Ju Nan <junan76@163.com>

[ Upstream commit d31fbbade43f880b7e59e2b3a72722fe2725d93f ]

HWSPNLCK_TIMEOUT is passed to hwspin_lock_timeout_in_atomic(), whose
timeout argument is in milliseconds, not microseconds:

  atomic_delay += HWSPINLOCK_RETRY_DELAY_US;
  if (atomic_delay > to * 1000)
          return -ETIMEDOUT;

So stm32mp_exti_set_type() asks for a 1 second timeout where the comment
next to the macro says it wants 1 millisecond. The semaphore is polled
with udelay() from a section that holds chip_data->rlock, a
raw_spinlock_t, so preemption stays disabled for the whole wait on every
configuration, PREEMPT_RT included.

The hwspinlock core documents this explicitly:

  If the mode is HWLOCK_IN_ATOMIC (called from an atomic context) the
  timeout is handled with busy-waiting delays, hence shall not exceed
  few msecs.

Fixes: 5257169ade8c ("irqchip/stm32-exti: Use the hwspin_lock_timeout_in_atomic() API")
Signed-off-by: Ju Nan <junan76@163.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Radu Rendec <radu@rendec.net>
Reviewed-by: Antonio Borneo <antonio.borneo@foss.st.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260821024756.24927-2-junan76@163.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/irqchip/irq-stm32mp-exti.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-stm32mp-exti.c b/drivers/irqchip/irq-stm32mp-exti.c
index ed43ced2d6ed1..fab88feae3e3d 100644
--- a/drivers/irqchip/irq-stm32mp-exti.c
+++ b/drivers/irqchip/irq-stm32mp-exti.c
@@ -24,7 +24,7 @@
 
 #define IRQS_PER_BANK			32
 
-#define HWSPNLCK_TIMEOUT		1000 /* usec */
+#define HWSPNLCK_TIMEOUT_MS		1
 
 #define EXTI_EnCIDCFGR(n)		(0x180 + (n) * 4)
 #define EXTI_HWCFGR1			0x3f0
@@ -503,7 +503,7 @@ static int stm32_exti_h_set_type(struct irq_data *d, unsigned int type)
 	raw_spin_lock(&chip_data->rlock);
 
 	if (hwlock) {
-		err = hwspin_lock_timeout_in_atomic(hwlock, HWSPNLCK_TIMEOUT);
+		err = hwspin_lock_timeout_in_atomic(hwlock, HWSPNLCK_TIMEOUT_MS);
 		if (err) {
 			pr_err("%s can't get hwspinlock (%d)\n", __func__, err);
 			goto unlock;
-- 
2.53.0