1 files changed, 77 insertions, 0 deletions
diff --git a/debian/patches-rt/0011-serial-8250_mtk-Use-port-lock-wrappers.patch b/debian/patches-rt/0011-serial-8250_mtk-Use-port-lock-wrappers.patch
new file mode 100644
index 000000000..a66818204
--- /dev/null
+++ b/debian/patches-rt/0011-serial-8250_mtk-Use-port-lock-wrappers.patch
@@ -0,0 +1,77 @@
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Thu, 14 Sep 2023 20:43:28 +0206
+Subject: [PATCH 011/134] serial: 8250_mtk: Use port lock wrappers
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz
+
+When a serial port is used for kernel console output, then all
+modifications to the UART registers which are done from other contexts,
+e.g. getty, termios, are interference points for the kernel console.
+
+So far this has been ignored and the printk output is based on the
+principle of hope. The rework of the console infrastructure which aims to
+support threaded and atomic consoles, requires to mark sections which
+modify the UART registers as unsafe. This allows the atomic write function
+to make informed decisions and eventually to restore operational state. It
+also allows to prevent the regular UART code from modifying UART registers
+while printk output is in progress.
+
+All modifications of UART registers are guarded by the UART port lock,
+which provides an obvious synchronization point with the console
+infrastructure.
+
+To avoid adding this functionality to all UART drivers, wrap the
+spin_[un]lock*() invocations for uart_port::lock into helper functions
+which just contain the spin_[un]lock*() invocations for now. In a
+subsequent step these helpers will gain the console synchronization
+mechanisms.
+
+Converted with coccinelle. No functional change.
+
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
+Signed-off-by: John Ogness <john.ogness@linutronix.de>
+Link: https://lore.kernel.org/r/20230914183831.587273-12-john.ogness@linutronix.de
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ drivers/tty/serial/8250/8250_mtk.c |    8 ++++----
+ 1 file changed, 4 insertions(+), 4 deletions(-)
+
+--- a/drivers/tty/serial/8250/8250_mtk.c
++++ b/drivers/tty/serial/8250/8250_mtk.c
+@@ -102,7 +102,7 @@ static void mtk8250_dma_rx_complete(void
+ 	if (data->rx_status == DMA_RX_SHUTDOWN)
+ 		return;
+ 
+-	spin_lock_irqsave(&up->port.lock, flags);
++	uart_port_lock_irqsave(&up->port, &flags);
+ 
+ 	dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
+ 	total = dma->rx_size - state.residue;
+@@ -128,7 +128,7 @@ static void mtk8250_dma_rx_complete(void
+ 
+ 	mtk8250_rx_dma(up);
+ 
+-	spin_unlock_irqrestore(&up->port.lock, flags);
++	uart_port_unlock_irqrestore(&up->port, flags);
+ }
+ 
+ static void mtk8250_rx_dma(struct uart_8250_port *up)
+@@ -368,7 +368,7 @@ mtk8250_set_termios(struct uart_port *po
+ 	 * Ok, we're now changing the port state.  Do it with
+ 	 * interrupts disabled.
+ 	 */
+-	spin_lock_irqsave(&port->lock, flags);
++	uart_port_lock_irqsave(port, &flags);
+ 
+ 	/*
+ 	 * Update the per-port timeout.
+@@ -416,7 +416,7 @@ mtk8250_set_termios(struct uart_port *po
+ 	if (uart_console(port))
+ 		up->port.cons->cflag = termios->c_cflag;
+ 
+-	spin_unlock_irqrestore(&port->lock, flags);
++	uart_port_unlock_irqrestore(port, flags);
+ 	/* Don't rewrite B0 */
+ 	if (tty_termios_baud_rate(termios))
+ 		tty_termios_encode_baud_rate(termios, baud, baud);