diff options
Diffstat (limited to 'debian/patches-rt/0004-serial-meson-Use-uart_prepare_sysrq_char.patch')
| -rw-r--r-- | debian/patches-rt/0004-serial-meson-Use-uart_prepare_sysrq_char.patch | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/debian/patches-rt/0004-serial-meson-Use-uart_prepare_sysrq_char.patch b/debian/patches-rt/0004-serial-meson-Use-uart_prepare_sysrq_char.patch new file mode 100644 index 000000000..d85b4e433 --- /dev/null +++ b/debian/patches-rt/0004-serial-meson-Use-uart_prepare_sysrq_char.patch @@ -0,0 +1,77 @@ +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Fri, 1 Mar 2024 22:45:17 +0100 +Subject: [PATCH 04/18] serial: meson: Use uart_prepare_sysrq_char(). +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz + +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 +Link: https://lore.kernel.org/r/20240301215246.891055-5-bigeasy@linutronix.de +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + drivers/tty/serial/meson_uart.c | 22 ++++++++-------------- + 1 file changed, 8 insertions(+), 14 deletions(-) + +--- a/drivers/tty/serial/meson_uart.c ++++ b/drivers/tty/serial/meson_uart.c +@@ -220,7 +220,7 @@ static void meson_receive_chars(struct u + 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( + 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(stru + 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(stru + 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, |