Hi Biju,
On Mon, Mar 20, 2023 at 11:53 AM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> 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: f9a2adcc9e90 ("arm64: dts: renesas: r9a07g044: Add SCI[0-1] nodes")
That's a DTS patch?
I'm wondering if this got broken accidentally by commit 93bcefd4c6bad4c6
("serial: sh-sci: Fix setting SCSCR_TIE while transferring data"),
which was probably never tested on SCI.
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> ---
> 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 b9cd27451f90..9079a8ea9132 100644
> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -597,6 +597,15 @@ 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);
> }
> }
> @@ -835,6 +844,12 @@ 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;
> }
>
> @@ -2581,8 +2596,14 @@ 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)) {
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
