Commit fb793b95 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Greg Kroah-Hartman
Browse files

serial: meson: Use uart_prepare_sysrq_char(). 



The port lock is a spinlock_t which is becomes a sleeping lock on PREEMPT_RT.
The driver splits the locking function into two parts: local_irq_save() and
uart_port_lock() and this breaks PREEMPT_RT.

Delay handling sysrq until port lock is dropped.
Remove the special case in the console write routine an always use the
complete locking function.

Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-amlogic@lists.infradead.org
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20240301215246.891055-5-bigeasy@linutronix.de


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8c1cbc5a

drivers/tty/serial/meson_uart.c

+8 −14
Original line number Diff line number Diff line
@@ -220,7 +220,7 @@ static void meson_receive_chars(struct uart_port *port) 
				continue;

		}



		if (uart_handle_sysrq_char(port, ch))

		if (uart_prepare_sysrq_char(port, ch))

			continue;



		if ((status & port->ignore_status_mask) == 0)
@@ -248,7 +248,7 @@ static irqreturn_t meson_uart_interrupt(int irq, void *dev_id) 
			meson_uart_start_tx(port);

	}



	uart_port_unlock(port);

	uart_unlock_and_check_sysrq(port);



	return IRQ_HANDLED;

}
@@ -556,18 +556,13 @@ static void meson_serial_port_write(struct uart_port *port, const char *s, 
				    u_int count)

{

	unsigned long flags;

	int locked;

	int locked = 1;

	u32 val, tmp;



	local_irq_save(flags);

	if (port->sysrq) {

		locked = 0;

	} else if (oops_in_progress) {

		locked = uart_port_trylock(port);

	} else {

		uart_port_lock(port);

		locked = 1;

	}

	if (oops_in_progress)

		locked = uart_port_trylock_irqsave(port, &flags);

	else

		uart_port_lock_irqsave(port, &flags);



	val = readl(port->membase + AML_UART_CONTROL);

	tmp = val & ~(AML_UART_TX_INT_EN | AML_UART_RX_INT_EN);
@@ -577,8 +572,7 @@ static void meson_serial_port_write(struct uart_port *port, const char *s, 
	writel(val, port->membase + AML_UART_CONTROL);



	if (locked)

		uart_port_unlock(port);

	local_irq_restore(flags);

		uart_port_unlock_irqrestore(port, flags);

}



static void meson_serial_console_write(struct console *co, const char *s,