diff options
Diffstat (limited to 'debian/patches-rt/0005-serial-msm-Use-uart_prepare_sysrq_char.patch')
| -rw-r--r-- | debian/patches-rt/0005-serial-msm-Use-uart_prepare_sysrq_char.patch | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/debian/patches-rt/0005-serial-msm-Use-uart_prepare_sysrq_char.patch b/debian/patches-rt/0005-serial-msm-Use-uart_prepare_sysrq_char.patch new file mode 100644 index 000000000..75c822db4 --- /dev/null +++ b/debian/patches-rt/0005-serial-msm-Use-uart_prepare_sysrq_char.patch @@ -0,0 +1,116 @@ +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Fri, 1 Mar 2024 22:45:18 +0100 +Subject: [PATCH 05/18] serial: msm: 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: Bjorn Andersson <andersson@kernel.org> +Cc: Konrad Dybcio <konrad.dybcio@linaro.org> +Cc: linux-arm-msm@vger.kernel.org +Link: https://lore.kernel.org/r/20240301215246.891055-6-bigeasy@linutronix.de +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + drivers/tty/serial/msm_serial.c | 33 ++++++++++----------------------- + 1 file changed, 10 insertions(+), 23 deletions(-) + +--- a/drivers/tty/serial/msm_serial.c ++++ b/drivers/tty/serial/msm_serial.c +@@ -588,16 +588,14 @@ static void msm_complete_rx_dma(void *ar + if (!(port->read_status_mask & MSM_UART_SR_RX_BREAK)) + flag = TTY_NORMAL; + +- uart_port_unlock_irqrestore(port, flags); +- sysrq = uart_handle_sysrq_char(port, dma->virt[i]); +- uart_port_lock_irqsave(port, &flags); ++ sysrq = uart_prepare_sysrq_char(port, dma->virt[i]); + if (!sysrq) + tty_insert_flip_char(tport, dma->virt[i], flag); + } + + msm_start_rx_dma(msm_port); + done: +- uart_port_unlock_irqrestore(port, flags); ++ uart_unlock_and_check_sysrq_irqrestore(port, flags); + + if (count) + tty_flip_buffer_push(tport); +@@ -763,9 +761,7 @@ static void msm_handle_rx_dm(struct uart + if (!(port->read_status_mask & MSM_UART_SR_RX_BREAK)) + flag = TTY_NORMAL; + +- uart_port_unlock(port); +- sysrq = uart_handle_sysrq_char(port, buf[i]); +- uart_port_lock(port); ++ sysrq = uart_prepare_sysrq_char(port, buf[i]); + if (!sysrq) + tty_insert_flip_char(tport, buf[i], flag); + } +@@ -825,9 +821,7 @@ static void msm_handle_rx(struct uart_po + else if (sr & MSM_UART_SR_PAR_FRAME_ERR) + flag = TTY_FRAME; + +- uart_port_unlock(port); +- sysrq = uart_handle_sysrq_char(port, c); +- uart_port_lock(port); ++ sysrq = uart_prepare_sysrq_char(port, c); + if (!sysrq) + tty_insert_flip_char(tport, c, flag); + } +@@ -948,11 +942,10 @@ static irqreturn_t msm_uart_irq(int irq, + struct uart_port *port = dev_id; + struct msm_port *msm_port = to_msm_port(port); + struct msm_dma *dma = &msm_port->rx_dma; +- unsigned long flags; + unsigned int misr; + u32 val; + +- uart_port_lock_irqsave(port, &flags); ++ uart_port_lock(port); + misr = msm_read(port, MSM_UART_MISR); + msm_write(port, 0, MSM_UART_IMR); /* disable interrupt */ + +@@ -984,7 +977,7 @@ static irqreturn_t msm_uart_irq(int irq, + msm_handle_delta_cts(port); + + msm_write(port, msm_port->imr, MSM_UART_IMR); /* restore interrupt */ +- uart_port_unlock_irqrestore(port, flags); ++ uart_unlock_and_check_sysrq(port); + + return IRQ_HANDLED; + } +@@ -1621,14 +1614,10 @@ static void __msm_console_write(struct u + num_newlines++; + count += num_newlines; + +- local_irq_save(flags); +- +- if (port->sysrq) +- locked = 0; +- else if (oops_in_progress) +- locked = uart_port_trylock(port); ++ if (oops_in_progress) ++ locked = uart_port_trylock_irqsave(port, &flags); + else +- uart_port_lock(port); ++ uart_port_lock_irqsave(port, &flags); + + if (is_uartdm) + msm_reset_dm_count(port, count); +@@ -1667,9 +1656,7 @@ static void __msm_console_write(struct u + } + + if (locked) +- uart_port_unlock(port); +- +- local_irq_restore(flags); ++ uart_port_unlock_irqrestore(port, flags); + } + + static void msm_console_write(struct console *co, const char *s, |