diff options
Diffstat (limited to 'debian/patches-rt/0001-serial-amba-pl011-Use-uart_prepare_sysrq_char.patch')
| -rw-r--r-- | debian/patches-rt/0001-serial-amba-pl011-Use-uart_prepare_sysrq_char.patch | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/debian/patches-rt/0001-serial-amba-pl011-Use-uart_prepare_sysrq_char.patch b/debian/patches-rt/0001-serial-amba-pl011-Use-uart_prepare_sysrq_char.patch new file mode 100644 index 000000000..9acb1fcaa --- /dev/null +++ b/debian/patches-rt/0001-serial-amba-pl011-Use-uart_prepare_sysrq_char.patch @@ -0,0 +1,92 @@ +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Fri, 1 Mar 2024 22:45:14 +0100 +Subject: [PATCH 01/18] serial: amba-pl011: 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: Russell King <linux@armlinux.org.uk> +Link: https://lore.kernel.org/r/20240301215246.891055-2-bigeasy@linutronix.de +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + drivers/tty/serial/amba-pl011.c | 24 ++++++++---------------- + 1 file changed, 8 insertions(+), 16 deletions(-) + +--- a/drivers/tty/serial/amba-pl011.c ++++ b/drivers/tty/serial/amba-pl011.c +@@ -348,10 +348,7 @@ static int pl011_fifo_to_tty(struct uart + flag = TTY_FRAME; + } + +- uart_port_unlock(&uap->port); +- sysrq = uart_handle_sysrq_char(&uap->port, ch & 255); +- uart_port_lock(&uap->port); +- ++ sysrq = uart_prepare_sysrq_char(&uap->port, ch & 255); + if (!sysrq) + uart_insert_char(&uap->port, ch, UART011_DR_OE, ch, flag); + } +@@ -1017,7 +1014,7 @@ static void pl011_dma_rx_callback(void * + ret = pl011_dma_rx_trigger_dma(uap); + + pl011_dma_rx_chars(uap, pending, lastbuf, false); +- uart_port_unlock_irq(&uap->port); ++ uart_unlock_and_check_sysrq(&uap->port); + /* + * Do this check after we picked the DMA chars so we don't + * get some IRQ immediately from RX. +@@ -1540,11 +1537,10 @@ static void check_apply_cts_event_workar + static irqreturn_t pl011_int(int irq, void *dev_id) + { + struct uart_amba_port *uap = dev_id; +- unsigned long flags; + unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT; + int handled = 0; + +- uart_port_lock_irqsave(&uap->port, &flags); ++ uart_port_lock(&uap->port); + status = pl011_read(uap, REG_RIS) & uap->im; + if (status) { + do { +@@ -1573,7 +1569,7 @@ static irqreturn_t pl011_int(int irq, vo + handled = 1; + } + +- uart_port_unlock_irqrestore(&uap->port, flags); ++ uart_unlock_and_check_sysrq(&uap->port); + + return IRQ_RETVAL(handled); + } +@@ -2322,13 +2318,10 @@ pl011_console_write(struct console *co, + + clk_enable(uap->clk); + +- local_irq_save(flags); +- if (uap->port.sysrq) +- locked = 0; +- else if (oops_in_progress) +- locked = uart_port_trylock(&uap->port); ++ if (oops_in_progress) ++ locked = uart_port_trylock_irqsave(&uap->port, &flags); + else +- uart_port_lock(&uap->port); ++ uart_port_lock_irqsave(&uap->port, &flags); + + /* + * First save the CR then disable the interrupts +@@ -2354,8 +2347,7 @@ pl011_console_write(struct console *co, + pl011_write(old_cr, uap, REG_CR); + + if (locked) +- uart_port_unlock(&uap->port); +- local_irq_restore(flags); ++ uart_port_unlock_irqrestore(&uap->port, flags); + + clk_disable(uap->clk); + } |