For SCI, the TE (transmit enable) must be set after setting TIE (transmit interrupt enable) or in the same instruction to start the transmission. Set TE bit in sci_start_tx() instead of set_termios() for SCI and clear TE bit, if circular buffer is empty in sci_transmit_chars().
Fixes: 93bcefd4c6ba ("serial: sh-sci: Fix setting SCSCR_TIE while transferring data") Cc: stable@vger.kernel.org Signed-off-by: Biju Das biju.das.jz@bp.renesas.com --- v3->v4: * Updated fixes tag. v3: * New patch --- drivers/tty/serial/sh-sci.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index 15954ca3e9dc..bcc4152ce043 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -596,6 +596,15 @@ static void sci_start_tx(struct uart_port *port) if (!s->chan_tx || port->type == PORT_SCIFA || port->type == PORT_SCIFB) { /* Set TIE (Transmit Interrupt Enable) bit in SCSCR */ ctrl = serial_port_in(port, SCSCR); + + /* + * For SCI, TE (transmit enable) must be set after setting TIE + * (transmit interrupt enable) or in the same instruction to start + * the transmit process. + */ + if (port->type == PORT_SCI) + ctrl |= SCSCR_TE; + serial_port_out(port, SCSCR, ctrl | SCSCR_TIE); } } @@ -834,6 +843,12 @@ static void sci_transmit_chars(struct uart_port *port) c = xmit->buf[xmit->tail]; xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); } else { + if (port->type == PORT_SCI) { + ctrl = serial_port_in(port, SCSCR); + ctrl &= ~SCSCR_TE; + serial_port_out(port, SCSCR, ctrl); + return; + } break; }
@@ -2580,8 +2595,14 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios, sci_set_mctrl(port, port->mctrl); }
- scr_val |= SCSCR_RE | SCSCR_TE | - (s->cfg->scscr & ~(SCSCR_CKE1 | SCSCR_CKE0)); + /* + * For SCI, TE (transmit enable) must be set after setting TIE + * (transmit interrupt enable) or in the same instruction to + * start the transmitting process. So skip setting TE here for SCI. + */ + if (port->type != PORT_SCI) + scr_val |= SCSCR_TE; + scr_val |= SCSCR_RE | (s->cfg->scscr & ~(SCSCR_CKE1 | SCSCR_CKE0)); serial_port_out(port, SCSCR, scr_val | s->hscif_tot); if ((srr + 1 == 5) && (port->type == PORT_SCIFA || port->type == PORT_SCIFB)) {