@@ -849,6 +849,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
u32 sr;
unsigned int size;
+ irqreturn_t ret = IRQ_NONE;
sr = readl_relaxed(port->membase + ofs->isr);
@@ -857,11 +858,14 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
(sr & USART_SR_TC)) {
stm32_usart_tc_interrupt_disable(port);
stm32_usart_rs485_rts_disable(port);
+ ret = IRQ_HANDLED;
}
- if ((sr & USART_SR_RTOF) && ofs->icr != UNDEF_REG)
+ if ((sr & USART_SR_RTOF) && ofs->icr != UNDEF_REG) {
writel_relaxed(USART_ICR_RTOCF,
port->membase + ofs->icr);
+ ret = IRQ_HANDLED;
+ }
if ((sr & USART_SR_WUF) && ofs->icr != UNDEF_REG) {
/* Clear wake up flag and disable wake up interrupt */
@@ -870,6 +874,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_WUFIE);
if (irqd_is_wakeup_set(irq_get_irq_data(port->irq)))
pm_wakeup_event(tport->tty->dev, 0);
+ ret = IRQ_HANDLED;
}
/*
@@ -884,6 +889,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
uart_unlock_and_check_sysrq(port);
if (size)
tty_flip_buffer_push(tport);
+ ret = IRQ_HANDLED;
}
}
@@ -891,6 +897,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
uart_port_lock(port);
stm32_usart_transmit_chars(port);
uart_port_unlock(port);
+ ret = IRQ_HANDLED;
}
/* Receiver timeout irq for DMA RX */
@@ -900,9 +907,10 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
uart_unlock_and_check_sysrq(port);
if (size)
tty_flip_buffer_push(tport);
+ ret = IRQ_HANDLED;
}
- return IRQ_HANDLED;
+ return ret;
}
static void stm32_usart_set_mctrl(struct uart_port *port, unsigned int mctrl)
If there is a stuck irq that the handler doesn't address, returning IRQ_HANDLED unconditionally makes it impossible for the irq core to detect the problem and disable the irq. So only return IRQ_HANDLED if an event was handled. A stuck irq is still problematic, but with this change at least it only makes the UART nonfunctional instead of occupying the (usually only) CPU by 100% and so stall the whole machine. Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver") Cc: stable@vger.kernel.org Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- drivers/tty/serial/stm32-usart.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)