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-rw-r--r--debian/patches-rt/0037-serial-meson-Use-port-lock-wrappers.patch168
1 files changed, 168 insertions, 0 deletions
diff --git a/debian/patches-rt/0037-serial-meson-Use-port-lock-wrappers.patch b/debian/patches-rt/0037-serial-meson-Use-port-lock-wrappers.patch
new file mode 100644
index 0000000000..d2efb460bc
--- /dev/null
+++ b/debian/patches-rt/0037-serial-meson-Use-port-lock-wrappers.patch
@@ -0,0 +1,168 @@
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Thu, 14 Sep 2023 20:43:54 +0206
+Subject: [PATCH 037/134] serial: meson: 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>
+Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
+Signed-off-by: John Ogness <john.ogness@linutronix.de>
+Link: https://lore.kernel.org/r/20230914183831.587273-38-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/meson_uart.c | 30 +++++++++++++++---------------
+ 1 file changed, 15 insertions(+), 15 deletions(-)
+
+--- a/drivers/tty/serial/meson_uart.c
++++ b/drivers/tty/serial/meson_uart.c
+@@ -129,14 +129,14 @@ static void meson_uart_shutdown(struct u
+
+ free_irq(port->irq, port);
+
+- spin_lock_irqsave(&port->lock, flags);
++ uart_port_lock_irqsave(port, &flags);
+
+ val = readl(port->membase + AML_UART_CONTROL);
+ val &= ~AML_UART_RX_EN;
+ val &= ~(AML_UART_RX_INT_EN | AML_UART_TX_INT_EN);
+ writel(val, port->membase + AML_UART_CONTROL);
+
+- spin_unlock_irqrestore(&port->lock, flags);
++ uart_port_unlock_irqrestore(port, flags);
+ }
+
+ static void meson_uart_start_tx(struct uart_port *port)
+@@ -238,7 +238,7 @@ static irqreturn_t meson_uart_interrupt(
+ {
+ struct uart_port *port = (struct uart_port *)dev_id;
+
+- spin_lock(&port->lock);
++ uart_port_lock(port);
+
+ if (!(readl(port->membase + AML_UART_STATUS) & AML_UART_RX_EMPTY))
+ meson_receive_chars(port);
+@@ -248,7 +248,7 @@ static irqreturn_t meson_uart_interrupt(
+ meson_uart_start_tx(port);
+ }
+
+- spin_unlock(&port->lock);
++ uart_port_unlock(port);
+
+ return IRQ_HANDLED;
+ }
+@@ -284,7 +284,7 @@ static int meson_uart_startup(struct uar
+ u32 val;
+ int ret = 0;
+
+- spin_lock_irqsave(&port->lock, flags);
++ uart_port_lock_irqsave(port, &flags);
+
+ val = readl(port->membase + AML_UART_CONTROL);
+ val |= AML_UART_CLEAR_ERR;
+@@ -301,7 +301,7 @@ static int meson_uart_startup(struct uar
+ val = (AML_UART_RECV_IRQ(1) | AML_UART_XMIT_IRQ(port->fifosize / 2));
+ writel(val, port->membase + AML_UART_MISC);
+
+- spin_unlock_irqrestore(&port->lock, flags);
++ uart_port_unlock_irqrestore(port, flags);
+
+ ret = request_irq(port->irq, meson_uart_interrupt, 0,
+ port->name, port);
+@@ -341,7 +341,7 @@ static void meson_uart_set_termios(struc
+ unsigned long flags;
+ u32 val;
+
+- spin_lock_irqsave(&port->lock, flags);
++ uart_port_lock_irqsave(port, &flags);
+
+ cflags = termios->c_cflag;
+ iflags = termios->c_iflag;
+@@ -405,7 +405,7 @@ static void meson_uart_set_termios(struc
+ AML_UART_FRAME_ERR;
+
+ uart_update_timeout(port, termios->c_cflag, baud);
+- spin_unlock_irqrestore(&port->lock, flags);
++ uart_port_unlock_irqrestore(port, flags);
+ }
+
+ static int meson_uart_verify_port(struct uart_port *port,
+@@ -464,14 +464,14 @@ static int meson_uart_poll_get_char(stru
+ u32 c;
+ unsigned long flags;
+
+- spin_lock_irqsave(&port->lock, flags);
++ uart_port_lock_irqsave(port, &flags);
+
+ if (readl(port->membase + AML_UART_STATUS) & AML_UART_RX_EMPTY)
+ c = NO_POLL_CHAR;
+ else
+ c = readl(port->membase + AML_UART_RFIFO);
+
+- spin_unlock_irqrestore(&port->lock, flags);
++ uart_port_unlock_irqrestore(port, flags);
+
+ return c;
+ }
+@@ -482,7 +482,7 @@ static void meson_uart_poll_put_char(str
+ u32 reg;
+ int ret;
+
+- spin_lock_irqsave(&port->lock, flags);
++ uart_port_lock_irqsave(port, &flags);
+
+ /* Wait until FIFO is empty or timeout */
+ ret = readl_poll_timeout_atomic(port->membase + AML_UART_STATUS, reg,
+@@ -506,7 +506,7 @@ static void meson_uart_poll_put_char(str
+ dev_err(port->dev, "Timeout waiting for UART TX EMPTY\n");
+
+ out:
+- spin_unlock_irqrestore(&port->lock, flags);
++ uart_port_unlock_irqrestore(port, flags);
+ }
+
+ #endif /* CONFIG_CONSOLE_POLL */
+@@ -563,9 +563,9 @@ static void meson_serial_port_write(stru
+ if (port->sysrq) {
+ locked = 0;
+ } else if (oops_in_progress) {
+- locked = spin_trylock(&port->lock);
++ locked = uart_port_trylock(port);
+ } else {
+- spin_lock(&port->lock);
++ uart_port_lock(port);
+ locked = 1;
+ }
+
+@@ -577,7 +577,7 @@ static void meson_serial_port_write(stru
+ writel(val, port->membase + AML_UART_CONTROL);
+
+ if (locked)
+- spin_unlock(&port->lock);
++ uart_port_unlock(port);
+ local_irq_restore(flags);
+ }
+