diff mbox series

[v4,3/5] tty: serial: sh-sci: Fix Tx on SCI IP

Message ID 20230321114753.75038-4-biju.das.jz@bp.renesas.com (mailing list archive)
State Superseded
Delegated to: Geert Uytterhoeven
Headers show
Series Renesas SCI fixes | expand

Commit Message

Biju Das March 21, 2023, 11:47 a.m. UTC 
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(-)

Comments

Biju Das April 6, 2023, 6:50 a.m. UTC | #1 
Hi All,

I split this patch into 2([1] & [2]) after fixing commit message
and merged with the series[3] to avoid any dependencies.

[1] https://lore.kernel.org/linux-renesas-soc/20230331113346.170602-4-biju.das.jz@bp.renesas.com/T/#u
[2] https://lore.kernel.org/linux-renesas-soc/20230331113346.170602-4-biju.das.jz@bp.renesas.com/T/#md8ae156345aed10bdeba764dcf2253f00b02e38c

[3] https://lore.kernel.org/linux-renesas-soc/20230331113346.170602-4-biju.das.jz@bp.renesas.com/T/#me7f60560fbf24bf361d70ccb6ba223e92a60de9b

Cheers,
Biju


> Subject: [PATCH v4 3/5] tty: serial: sh-sci: Fix Tx on SCI IP
> 
> 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)) {
> --
> 2.25.1
diff mbox series

Patch

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)) {