On 04/29/2016 05:58 AM, Geert Uytterhoeven wrote:
> Correct pin initialization on (H)SCIF:
> - RTS must be deasserted (it's active low),
> - SCK must be an input, as it may be used as the optional external
> clock input.
>
> Initial pin configuration must always be done:
> - Regardless of the presence of dedicated RTS and CTS pins: if the
> register exists, the RTS/CTS bits exist, too,
> - Regardless of hardware flow control being enabled or not: RTS must
> be deasserted.
This is always setting RTS active; why?
Normally you want to program RTS only in response to ->set_mctrl()
from serial core. For example, this will set RTS active even though
baud might be set to B0.
> Signed-off-by: Geert Uytterhoeven <geert+rene...@glider.be>
> ---
> v2:
> - New.
> ---
> drivers/tty/serial/sh-sci.c | 23 ++++++++---------------
> 1 file changed, 8 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
> index ce7bd165929ea078..c46999f20917964e 100644
> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -712,21 +712,14 @@ static void sci_init_pins(struct uart_port *port,
> unsigned int cflag)
> return;
> }
>
> - /*
> - * For the generic path SCSPTR is necessary. Bail out if that's
> - * unavailable, too.
> - */
> - if (!sci_getreg(port, SCSPTR)->size)
> - return;
> -
> - if ((s->cfg->capabilities & SCIx_HAVE_RTSCTS) &&
> - ((!(cflag & CRTSCTS)))) {
> - unsigned short status;
> -
> - status = serial_port_in(port, SCSPTR);
> - status &= ~SCSPTR_CTSIO;
> - status |= SCSPTR_RTSIO;
> - serial_port_out(port, SCSPTR, status); /* Set RTS = 1 */
> + if (sci_getreg(port, SCSPTR)->size) {
> + u16 status = serial_port_in(port, SCSPTR);
> +
> + /* RTS# is output, driven 1 */
> + status |= SCSPTR_RTSIO | SCSPTR_RTSDT;
> + /* CTS# and SCK are inputs */
> + status &= ~(SCSPTR_CTSIO | SCSPTR_SCKIO);
> + serial_port_out(port, SCSPTR, status);
> }
> }
>
>
