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Subject[PATCH v2 3/3] serial: sh-sci: Fix (AUTO)RTS in sci_init_pins()
Date
If a UART has dedicated RTS/CTS pins, and hardware control flow is
disabled (or AUTORTS is not yet effective), changing any serial port
configuration deasserts RTS, as .set_termios() calls sci_init_pins().

To fix this, consider the current (AUTO)RTS state when (re)initializing
the pins. Note that for SCIFA/SCIFB, AUTORTS needs explicit
configuration of the RTS# pin function, while (H)SCIF handles this
automatically.

Fixes: d2b9775d795ec05f ("serial: sh-sci: Correct pin initialization on (H)SCIF")
Fixes: e9d7a45a03991349 ("serial: sh-sci: Add pin initialization for SCIFA/SCIFB")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v2:
- New.
---
drivers/tty/serial/sh-sci.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 6e405fb5a23f0b4a..71707e8e6e3ffe76 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -683,24 +683,37 @@ static void sci_init_pins(struct uart_port *port, unsigned int cflag)
}

if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) {
+ u16 data = serial_port_in(port, SCPDR);
u16 ctrl = serial_port_in(port, SCPCR);

/* Enable RXD and TXD pin functions */
ctrl &= ~(SCPCR_RXDC | SCPCR_TXDC);
if (to_sci_port(port)->has_rtscts) {
- /* RTS# is output, driven 1 */
- ctrl |= SCPCR_RTSC;
- serial_port_out(port, SCPDR,
- serial_port_in(port, SCPDR) | SCPDR_RTSD);
+ /* RTS# is output, active low, unless autorts */
+ if (!(port->mctrl & TIOCM_RTS)) {
+ ctrl |= SCPCR_RTSC;
+ data |= SCPDR_RTSD;
+ } else if (!s->autorts) {
+ ctrl |= SCPCR_RTSC;
+ data &= ~SCPDR_RTSD;
+ } else {
+ /* Enable RTS# pin function */
+ ctrl &= ~SCPCR_RTSC;
+ }
/* Enable CTS# pin function */
ctrl &= ~SCPCR_CTSC;
}
+ serial_port_out(port, SCPDR, data);
serial_port_out(port, SCPCR, ctrl);
} else if (sci_getreg(port, SCSPTR)->size) {
u16 status = serial_port_in(port, SCSPTR);

- /* RTS# is output, driven 1 */
- status |= SCSPTR_RTSIO | SCSPTR_RTSDT;
+ /* RTS# is always output; and active low, unless autorts */
+ status |= SCSPTR_RTSIO;
+ if (!(port->mctrl & TIOCM_RTS))
+ status |= SCSPTR_RTSDT;
+ else if (!s->autorts)
+ status &= ~SCSPTR_RTSDT;
/* CTS# and SCK are inputs */
status &= ~(SCSPTR_CTSIO | SCSPTR_SCKIO);
serial_port_out(port, SCSPTR, status);
--
2.7.4
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