From 6a7b9f002eca6788d346c16a6ff0c218b41f8d1d Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Wed, 26 Jan 2022 14:33:58 +0100 Subject: Revert "tty: serial: Use fifo in 8250 console driver" This reverts commit 5021d709b31b8a14317998a33cbc78be0de9ab30. The patch is still a bit buggy, and this breaks some other hardware types. It needs to be resubmitted in a non-buggy way, and make sure the other hardware types also continue to work properly. Fixes: 5021d709b31b ("tty: serial: Use fifo in 8250 console driver") Reported-by: Sebastian Andrzej Siewior Reported-by: Jon Hunter Link: https://lore.kernel.org/r/Ye/1+Z8mEzbKbrqG@linutronix.de Link: https://lore.kernel.org/r/a1ac6254-f79e-d131-fa2a-c7ad714c6d4a@nvidia.com Cc: Wander Lairson Costa Cc: Andy Shevchenko Cc: Jiri Slaby Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_port.c | 61 ++++--------------------------------- 1 file changed, 6 insertions(+), 55 deletions(-) (limited to 'drivers') diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 2abb3de11a48..3b12bfc1ed67 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2056,7 +2056,10 @@ static void serial8250_break_ctl(struct uart_port *port, int break_state) serial8250_rpm_put(up); } -static void wait_for_lsr(struct uart_8250_port *up, int bits) +/* + * Wait for transmitter & holding register to empty + */ +static void wait_for_xmitr(struct uart_8250_port *up, int bits) { unsigned int status, tmout = 10000; @@ -2073,16 +2076,6 @@ static void wait_for_lsr(struct uart_8250_port *up, int bits) udelay(1); touch_nmi_watchdog(); } -} - -/* - * Wait for transmitter & holding register to empty - */ -static void wait_for_xmitr(struct uart_8250_port *up, int bits) -{ - unsigned int tmout; - - wait_for_lsr(up, bits); /* Wait up to 1s for flow control if necessary */ if (up->port.flags & UPF_CONS_FLOW) { @@ -3332,35 +3325,6 @@ static void serial8250_console_restore(struct uart_8250_port *up) serial8250_out_MCR(up, UART_MCR_DTR | UART_MCR_RTS); } -/* - * Print a string to the serial port using the device FIFO - * - * It sends fifosize bytes and then waits for the fifo - * to get empty. - */ -static void serial8250_console_fifo_write(struct uart_8250_port *up, - const char *s, unsigned int count) -{ - int i; - const char *end = s + count; - unsigned int fifosize = up->port.fifosize; - bool cr_sent = false; - - while (s != end) { - wait_for_lsr(up, UART_LSR_THRE); - - for (i = 0; i < fifosize && s != end; ++i) { - if (*s == '\n' && !cr_sent) { - serial_out(up, UART_TX, '\r'); - cr_sent = true; - } else { - serial_out(up, UART_TX, *s++); - cr_sent = false; - } - } - } -} - /* * Print a string to the serial port trying not to disturb * any possible real use of the port... @@ -3376,7 +3340,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, struct uart_8250_em485 *em485 = up->em485; struct uart_port *port = &up->port; unsigned long flags; - unsigned int ier, use_fifo; + unsigned int ier; int locked = 1; touch_nmi_watchdog(); @@ -3408,20 +3372,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, mdelay(port->rs485.delay_rts_before_send); } - use_fifo = (up->capabilities & UART_CAP_FIFO) && - port->fifosize > 1 && - (serial_port_in(port, UART_FCR) & UART_FCR_ENABLE_FIFO) && - /* - * After we put a data in the fifo, the controller will send - * it regardless of the CTS state. Therefore, only use fifo - * if we don't use control flow. - */ - !(up->port.flags & UPF_CONS_FLOW); - - if (likely(use_fifo)) - serial8250_console_fifo_write(up, s, count); - else - uart_console_write(port, s, count, serial8250_console_putchar); + uart_console_write(port, s, count, serial8250_console_putchar); /* * Finally, wait for transmitter to become empty -- cgit v1.2.3