FAILED: patch "[PATCH] serial: stm32: Merge hard IRQ and threaded IRQ handling into" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-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 <[email protected]>.

Possible dependencies:

3f6c02fa712b ("serial: stm32: Merge hard IRQ and threaded IRQ handling into single IRQ handler") 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")
cc58d0a3f0a4 ("serial: stm32: re-introduce an irq flag condition in usart_receive_chars") 59bd4eedf118 ("serial: stm32: use the defined variable to simplify code") a7770a4bfcf4 ("serial: stm32: defer probe for dma devices")
cea37afd28f1 ("serial: stm32: defer sysrq processing")
e359b4411c28 ("serial: stm32: fix threaded interrupt handling")
3d530017bef1 ("serial: stm32: update wakeup IRQ management")
c0f3332cb5f2 ("serial: stm32: clean wakeup handling in serial_suspend") 1631eeeaf084 ("serial: stm32: rework wakeup management")
9f77d19207a0 ("serial: stm32: add FIFO flush when port is closed")
12761869f0ef ("serial: stm32: fix wake-up flag handling")
ad7676812437 ("serial: stm32: fix a deadlock condition with wakeup event") 25a8e7611da5 ("serial: stm32: fix TX and RX FIFO thresholds")
f4518a8a75f5 ("serial: stm32: fix startup by enabling usart for reception") 87fd0741d6dc ("serial: stm32: fix probe and remove order for dma")

thanks,

greg k-h

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

From 3f6c02fa712bd453871877fe1d1969625617471e Mon Sep 17 00:00:00 2001
From: Marek Vasut <[email protected]>
Date: Fri, 20 Jan 2023 17:03:32 +0100
Subject: [PATCH] serial: stm32: Merge hard IRQ and threaded IRQ handling into
single IRQ handler

Requesting an interrupt with IRQF_ONESHOT will run the primary handler in the hard-IRQ context even in the force-threaded mode. The force-threaded mode is used by PREEMPT_RT in order to avoid acquiring sleeping locks (spinlock_t) in hard-IRQ context. This combination makes it impossible and leads to "sleeping while atomic" warnings.

Use one interrupt handler for both handlers (primary and secondary) and drop the IRQF_ONESHOT flag which is not needed.

index a1490033aa16..409e91d6829a 100644
@@ -797,25 +797,11 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
 		spin_unlock(&port->lock);
 	}
 
-	if (stm32_usart_rx_dma_enabled(port))
-		return IRQ_WAKE_THREAD;
-	else
-		return IRQ_HANDLED;
-}
-
-static irqreturn_t stm32_usart_threaded_interrupt(int irq, void *ptr)
-{
-	struct uart_port *port = ptr;
-	struct tty_port *tport = &port->state->port;
-	struct stm32_port *stm32_port = to_stm32_port(port);
-	unsigned int size;
-	unsigned long flags;
-
 	/* Receiver timeout irq for DMA RX */
-	if (!stm32_port->throttled) {
-		spin_lock_irqsave(&port->lock, flags);
+	if (stm32_usart_rx_dma_enabled(port) && !stm32_port->throttled) {
+		spin_lock(&port->lock);
 		size = stm32_usart_receive_chars(port, false);
-		uart_unlock_and_check_sysrq_irqrestore(port, flags);
+		uart_unlock_and_check_sysrq(port);
 		if (size)
 			tty_flip_buffer_push(tport);
 	}

@@ -1015,10 +1001,8 @@ static int stm32_usart_startup(struct uart_port *port)
 	u32 val;
 	int ret;
 
-	ret = request_threaded_irq(port->irq, stm32_usart_interrupt,
-				   stm32_usart_threaded_interrupt,
-				   IRQF_ONESHOT | IRQF_NO_SUSPEND,
-				   name, port);
+	ret = request_irq(port->irq, stm32_usart_interrupt,
+			  IRQF_NO_SUSPEND, name, port);
 	if (ret)
 		return ret;
 

@@ -1601,13 +1585,6 @@ static int stm32_usart_of_dma_rx_probe(struct stm32_port *stm32port,
 	struct dma_slave_config config;
 	int ret;
 
-	/*
-	 * Using DMA and threaded handler for the console could lead to
-	 * deadlocks.
-	 */
-	if (uart_console(port))
-		return -ENODEV;
-
 	stm32port->rx_buf = dma_alloc_coherent(dev, RX_BUF_L,
 					       &stm32port->rx_dma_buf,
 					       GFP_KERNEL);