Messages in this thread Patch in this message | | | From | Giulio Benetti <> | Subject | [PATCH 4/4] serial: 8250_dw: treat rpm suspend with -EBUSY if RS485 ON and RTS_AFTER_SEND | Date | Wed, 6 Jun 2018 11:51:53 +0200 |
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If rs485 is on and RTS_AFTER_SEND it means that in idle state rts pin must be asserted, othwerwise rs485 transceiver will enter tx state. dw8250 when clocks are stopped keeps rts line de-asserted(high), resulting in keeping rs485 transceiver in tx state when port is idle.
Check if rs485 is on with RTS_AFTER_SEND set, if so return -EBUSY in rpm_suspend,
Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com> --- drivers/tty/serial/8250/8250_dw.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index 888280ff5451..6b0ee6dc8ad0 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -668,6 +668,11 @@ static int dw8250_resume(struct device *dev) static int dw8250_runtime_suspend(struct device *dev) { struct dw8250_data *data = dev_get_drvdata(dev); + struct uart_8250_port *up = serial8250_get_port(data->line); + struct uart_port *p = &up->port; + + if (p->rs485.flags & (SER_RS485_ENABLED | SER_RS485_RTS_AFTER_SEND)) + return -EBUSY; if (!IS_ERR(data->clk)) clk_disable_unprepare(data->clk); -- 2.17.1
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