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Revert "tty: serial: Use fifo in 8250 console driver"

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This reverts commit 5021d709b3.

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: 5021d709b3 ("tty: serial: Use fifo in 8250 console driver")
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reported-by: Jon Hunter <jonathanh@nvidia.com>
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 <wander@redhat.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2022-01-26 14:33:58 +01:00
parent e783362eb5
commit 6a7b9f002e
1 changed files with 6 additions and 55 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

61
drivers/tty/serial/8250/8250_port.c
View file

@ -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