public-mirrors/linux
1
0
Fork 0
mirror of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-08-05 16:54:27 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

tty: serial: imx: Add fast path when rs485 delays are 0

Browse source 
Right now, even when `delay_rts_before_send` and `delay_rts_after_send`
are 0, the hrtimer is triggered (with timeout 0) which can introduce a
few 100us of additional overhead on slower i.MX platforms.

Implement a fast path when the delays are 0, where the RTS signal is
toggled immediately instead of going through an hrtimer.  This fast path
behaves identical to the code before delay support was implemented.

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Harald Seiler <hws@denx.de>
Link: https://lore.kernel.org/r/20220119145204.238767-1-hws@denx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Harald Seiler 2022-01-19 15:52:03 +01:00 • committed by Greg Kroah-Hartman
parent fcc446c8aa
commit 582e9a24fc
1 changed files with 14 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

18
drivers/tty/serial/imx.c
View file

@ -455,9 +455,14 @@ static void imx_uart_stop_tx(struct uart_port *port)
if (port->rs485.flags & SER_RS485_ENABLED) {
if (sport->tx_state == SEND) {
sport->tx_state = WAIT_AFTER_SEND;
start_hrtimer_ms(&sport->trigger_stop_tx,
if (port->rs485.delay_rts_after_send > 0) {
start_hrtimer_ms(&sport->trigger_stop_tx,
port->rs485.delay_rts_after_send);
return;
return;
}
/* continue without any delay */
}
if (sport->tx_state == WAIT_AFTER_RTS ||
@ -698,9 +703,14 @@ static void imx_uart_start_tx(struct uart_port *port)
imx_uart_stop_rx(port);
sport->tx_state = WAIT_AFTER_RTS;
start_hrtimer_ms(&sport->trigger_start_tx,
if (port->rs485.delay_rts_before_send > 0) {
start_hrtimer_ms(&sport->trigger_start_tx,
port->rs485.delay_rts_before_send);
return;
return;
}
/* continue without any delay */
}
if (sport->tx_state == WAIT_AFTER_SEND