aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2018-12-20 07:29:11 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-20 07:29:11 -0800
commitbfd7bd5b49c84aac9068bff7635e94ce038475ec (patch)
tree3fcae6616773a9075a88738dda5b194b28a5dcbc
parentMerge tag 'usb-4.20-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb (diff)
parentRevert "serial: 8250: Fix clearing FIFOs in RS485 mode again" (diff)
downloadlinux-dev-bfd7bd5b49c84aac9068bff7635e94ce038475ec.tar.xz
linux-dev-bfd7bd5b49c84aac9068bff7635e94ce038475ec.zip
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"
-rw-r--r--drivers/tty/serial/8250/8250_port.c29
1 files changed, 5 insertions, 24 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index f776b3eafb96..3f779d25ec0c 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -552,30 +552,11 @@ static unsigned int serial_icr_read(struct uart_8250_port *up, int offset)
*/
static void serial8250_clear_fifos(struct uart_8250_port *p)
{
- unsigned char fcr;
- unsigned char clr_mask = UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT;
-
if (p->capabilities & UART_CAP_FIFO) {
- /*
- * Make sure to avoid changing FCR[7:3] and ENABLE_FIFO bits.
- * In case ENABLE_FIFO is not set, there is nothing to flush
- * so just return. Furthermore, on certain implementations of
- * the 8250 core, the FCR[7:3] bits may only be changed under
- * specific conditions and changing them if those conditions
- * are not met can have nasty side effects. One such core is
- * the 8250-omap present in TI AM335x.
- */
- fcr = serial_in(p, UART_FCR);
-
- /* FIFO is not enabled, there's nothing to clear. */
- if (!(fcr & UART_FCR_ENABLE_FIFO))
- return;
-
- fcr |= clr_mask;
- serial_out(p, UART_FCR, fcr);
-
- fcr &= ~clr_mask;
- serial_out(p, UART_FCR, fcr);
+ serial_out(p, UART_FCR, UART_FCR_ENABLE_FIFO);
+ serial_out(p, UART_FCR, UART_FCR_ENABLE_FIFO |
+ UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
+ serial_out(p, UART_FCR, 0);
}
}
@@ -1467,7 +1448,7 @@ static void __do_stop_tx_rs485(struct uart_8250_port *p)
* Enable previously disabled RX interrupts.
*/
if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
- serial8250_clear_fifos(p);
+ serial8250_clear_and_reinit_fifos(p);
p->ier |= UART_IER_RLSI | UART_IER_RDI;
serial_port_out(&p->port, UART_IER, p->ier);