The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 13c785323b36b845300b256d0e5963c3727667d7 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024042344-phonics-simile-0b3c@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

13c785323b36 ("serial: stm32: Return IRQ_NONE in the ISR if no handling happend") c5d06662551c ("serial: stm32: Use port lock wrappers") a01ae50d7eae ("serial: stm32: replace access to DMAR bit by dmaengine_pause/resume") 7f28bcea824e ("serial: stm32: group dma pause/resume error handling into single function") 00d1f9c6af0d ("serial: stm32: modify parameter and rename stm32_usart_rx_dma_enabled") db89728abad5 ("serial: stm32: avoid clearing DMAT bit during transfer") 3f6c02fa712b ("serial: stm32: Merge hard IRQ and threaded IRQ handling into single IRQ handler") d7c76716169d ("serial: stm32: Use TC interrupt to deassert GPIO RTS in RS485 mode") 3bcea529b295 ("serial: stm32: Factor out GPIO RTS toggling into separate function") 037b91ec7729 ("serial: stm32: fix software flow control transfer") d3d079bde07e ("serial: stm32: prevent TDR register overwrite when sending x_char") 195437d14fb4 ("serial: stm32: correct loop for dma error handling") 2a3bcfe03725 ("serial: stm32: fix flow control transfer in DMA mode") 9a135f16d228 ("serial: stm32: rework TX DMA state condition") 56a23f9319e8 ("serial: stm32: move tx dma terminate DMA to shutdown") 6333a4850621 ("serial: stm32: push DMA RX data before suspending") 6eeb348c8482 ("serial: stm32: terminate / restart DMA transfer at suspend / resume") e0abc903deea ("serial: stm32: rework RX dma initialization and release") d1ec8a2eabe9 ("serial: stm32: update throttle and unthrottle ops for dma mode") 33bb2f6ac308 ("serial: stm32: rework RX over DMA")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 13c785323b36b845300b256d0e5963c3727667d7 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= u.kleine-koenig@pengutronix.de Date: Wed, 17 Apr 2024 11:03:27 +0200 Subject: [PATCH] serial: stm32: Return IRQ_NONE in the ISR if no handling happend MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

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 Link: https://lore.kernel.org/r/5f92603d0dfd8a5b8014b2b10a902d91e0bb881f.171334416... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 58d169e5c1db..d60cbac69194 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -861,6 +861,7 @@ 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);

@@ -869,11 +870,14 @@ 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 */ @@ -882,6 +886,7 @@ 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; }

/* @@ -896,6 +901,7 @@ 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; } }

@@ -903,6 +909,7 @@ 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 */ @@ -912,9 +919,10 @@ 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)