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authorLukas Wunner <lukas@wunner.de>2020-03-27 15:38:16 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-03-27 15:45:54 +0100
commit8d5b305484e8a3216eeb700ed6c6de870306adbd (patch)
tree0d91065810f0456a3bc4aa4c3bf9e8ae00ae3452 /drivers/tty
parent4e36f94e996ebee8a919c6cd419f55e4d08ad4e3 (diff)
downloadlinux-8d5b305484e8a3216eeb700ed6c6de870306adbd.tar.bz2
serial: 8250: Optimize irq enable after console write
Commit 7f9803072ff6 ("serial: 8250: Support console on software emulated rs485 ports") amended serial8250_console_write() with rs485 support, but positioned the invocation of ->rs485_stop_tx() after re-enablement of interrupts. The irq handler and ->console_write() are serialized with the port spinlock, so no problem there, but due to the rs485 delay, the irq handler may unnecessarily spin for a while. Avoid that by moving ->rs485_stop_tx() before re-enablement of interrupts, which also mirrors the order at the beginning of serial8250_console_write(). Signed-off-by: Lukas Wunner <lukas@wunner.de> Link: https://lore.kernel.org/r/019839cb1f61b01210b6ff9ac9f9079ca77f8411.1585319447.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/8250/8250_port.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index a1d3aef3c406..f77bf820b7a3 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -3268,7 +3268,6 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
* and restore the IER
*/
wait_for_xmitr(up, BOTH_EMPTY);
- serial_port_out(port, UART_IER, ier);
if (em485) {
mdelay(port->rs485.delay_rts_after_send);
@@ -3276,6 +3275,8 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
up->rs485_stop_tx(up);
}
+ serial_port_out(port, UART_IER, ier);
+
/*
* The receive handling will happen properly because the
* receive ready bit will still be set; it is not cleared