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Diffstat (limited to '')
-rw-r--r-- | debian/patches-rt/0011-serial-8250_mtk-Use-port-lock-wrappers.patch | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/debian/patches-rt/0011-serial-8250_mtk-Use-port-lock-wrappers.patch b/debian/patches-rt/0011-serial-8250_mtk-Use-port-lock-wrappers.patch new file mode 100644 index 0000000000..a668182042 --- /dev/null +++ b/debian/patches-rt/0011-serial-8250_mtk-Use-port-lock-wrappers.patch @@ -0,0 +1,77 @@ +From: Thomas Gleixner <tglx@linutronix.de> +Date: Thu, 14 Sep 2023 20:43:28 +0206 +Subject: [PATCH 011/134] serial: 8250_mtk: 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> +Reviewed-by: Chen-Yu Tsai <wenst@chromium.org> +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Link: https://lore.kernel.org/r/20230914183831.587273-12-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/8250/8250_mtk.c | 8 ++++---- + 1 file changed, 4 insertions(+), 4 deletions(-) + +--- a/drivers/tty/serial/8250/8250_mtk.c ++++ b/drivers/tty/serial/8250/8250_mtk.c +@@ -102,7 +102,7 @@ static void mtk8250_dma_rx_complete(void + if (data->rx_status == DMA_RX_SHUTDOWN) + return; + +- spin_lock_irqsave(&up->port.lock, flags); ++ uart_port_lock_irqsave(&up->port, &flags); + + dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state); + total = dma->rx_size - state.residue; +@@ -128,7 +128,7 @@ static void mtk8250_dma_rx_complete(void + + mtk8250_rx_dma(up); + +- spin_unlock_irqrestore(&up->port.lock, flags); ++ uart_port_unlock_irqrestore(&up->port, flags); + } + + static void mtk8250_rx_dma(struct uart_8250_port *up) +@@ -368,7 +368,7 @@ mtk8250_set_termios(struct uart_port *po + * Ok, we're now changing the port state. Do it with + * interrupts disabled. + */ +- spin_lock_irqsave(&port->lock, flags); ++ uart_port_lock_irqsave(port, &flags); + + /* + * Update the per-port timeout. +@@ -416,7 +416,7 @@ mtk8250_set_termios(struct uart_port *po + if (uart_console(port)) + up->port.cons->cflag = termios->c_cflag; + +- spin_unlock_irqrestore(&port->lock, flags); ++ uart_port_unlock_irqrestore(port, flags); + /* Don't rewrite B0 */ + if (tty_termios_baud_rate(termios)) + tty_termios_encode_baud_rate(termios, baud, baud); |