Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'tty-4.20-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/serial fix from Greg KH:
"Here is a single fix, a revert, for the 8250 serial driver to resolve
a reported problem.
There was some attempted patches to fix the issue, but people are
arguing about them, so reverting the patch to revert back to the 4.19
and older behavior is the best thing to do at this late in the release
cycle.
The revert has been in linux-next with no reported issues"
* tag 'tty-4.20-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
Revert "serial: 8250: Fix clearing FIFOs in RS485 mode again"
+5
-24
+5
-24
drivers/tty/serial/8250/8250_port.c
+5
-24
drivers/tty/serial/8250/8250_port.c
···
552
552
*/
553
553
static void serial8250_clear_fifos(struct uart_8250_port *p)
554
554
{
555
-
unsigned char fcr;
556
-
unsigned char clr_mask = UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT;
557
-
558
555
if (p->capabilities & UART_CAP_FIFO) {
559
-
/*
560
-
* Make sure to avoid changing FCR[7:3] and ENABLE_FIFO bits.
561
-
* In case ENABLE_FIFO is not set, there is nothing to flush
562
-
* so just return. Furthermore, on certain implementations of
563
-
* the 8250 core, the FCR[7:3] bits may only be changed under
564
-
* specific conditions and changing them if those conditions
565
-
* are not met can have nasty side effects. One such core is
566
-
* the 8250-omap present in TI AM335x.
567
-
*/
568
-
fcr = serial_in(p, UART_FCR);
569
-
570
-
/* FIFO is not enabled, there's nothing to clear. */
571
-
if (!(fcr & UART_FCR_ENABLE_FIFO))
572
-
return;
573
-
574
-
fcr |= clr_mask;
575
-
serial_out(p, UART_FCR, fcr);
576
-
577
-
fcr &= ~clr_mask;
578
-
serial_out(p, UART_FCR, fcr);
556
+
serial_out(p, UART_FCR, UART_FCR_ENABLE_FIFO);
557
+
serial_out(p, UART_FCR, UART_FCR_ENABLE_FIFO |
558
+
UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
559
+
serial_out(p, UART_FCR, 0);
579
560
}
580
561
}
581
562
···
1448
1467
* Enable previously disabled RX interrupts.
1449
1468
*/
1450
1469
if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
1451
-
serial8250_clear_fifos(p);
1470
+
serial8250_clear_and_reinit_fifos(p);
1452
1471
1453
1472
p->ier |= UART_IER_RLSI | UART_IER_RDI;
1454
1473
serial_port_out(&p->port, UART_IER, p->ier);