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serial: omap: don't disable rs485 if rts gpio is missing

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There are rs485 transceivers (e.g. MAX13487E/MAX13488E) which
automatically disable or enable the driver and receiver to keep the bus
in the correct state.
In these cases we don't need a GPIO for flow control.

Fixes: 4a0ac0f55b ("OMAP: add RS485 support")
Signed-off-by: Dario Binacchi <dariobin@libero.it>
Link: https://lore.kernel.org/r/20210415210945.25863-1-dariobin@libero.it
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dario Binacchi 2021-04-15 23:09:45 +02:00 committed by Greg Kroah-Hartman
parent cea37afd28
commit 45f6b6db53
1 changed files with 4 additions and 8 deletions
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12
drivers/tty/serial/omap-serial.c
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@ -302,7 +302,8 @@ static void serial_omap_stop_tx(struct uart_port *port)
serial_out(up, UART_OMAP_SCR, up->scr);
res = (port->rs485.flags & SER_RS485_RTS_AFTER_SEND) ?
1 : 0;
if (gpiod_get_value(up->rts_gpiod) != res) {
if (up->rts_gpiod &&
gpiod_get_value(up->rts_gpiod) != res) {
if (port->rs485.delay_rts_after_send > 0)
mdelay(
port->rs485.delay_rts_after_send);
@ -411,7 +412,7 @@ static void serial_omap_start_tx(struct uart_port *port)
/* if rts not already enabled */
res = (port->rs485.flags & SER_RS485_RTS_ON_SEND) ? 1 : 0;
if (gpiod_get_value(up->rts_gpiod) != res) {
if (up->rts_gpiod && gpiod_get_value(up->rts_gpiod) != res) {
gpiod_set_value(up->rts_gpiod, res);
if (port->rs485.delay_rts_before_send > 0)
mdelay(port->rs485.delay_rts_before_send);
@ -1407,18 +1408,13 @@ serial_omap_config_rs485(struct uart_port *port, struct serial_rs485 *rs485)
/* store new config */
port->rs485 = *rs485;
/*
* Just as a precaution, only allow rs485
* to be enabled if the gpio pin is valid
*/
if (up->rts_gpiod) {
/* enable / disable rts */
val = (port->rs485.flags & SER_RS485_ENABLED) ?
SER_RS485_RTS_AFTER_SEND : SER_RS485_RTS_ON_SEND;
val = (port->rs485.flags & val) ? 1 : 0;
gpiod_set_value(up->rts_gpiod, val);
} else
port->rs485.flags &= ~SER_RS485_ENABLED;
}
/* Enable interrupts */
up->ier = mode;