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serial: sh-sci: Make sure status register SCxSR is read in correct sequence 

For SCIF and HSCIF interfaces the SCxSR register holds the status of
data that is to be read next from SCxRDR register, But where as for
SCIFA and SCIFB interfaces SCxSR register holds status of data that is
previously read from SCxRDR register.

This patch makes sure the status register is read depending on the port
types so that errors are caught accordingly.

Cc: <stable@vger.kernel.org>
Signed-off-by: Kazuhiro Fujita <kazuhiro.fujita.jg@renesas.com>
Signed-off-by: Hao Bui <hao.bui.yg@renesas.com>
Signed-off-by: KAZUMI HARADA <kazumi.harada.rh@renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/1585333048-31828-1-git-send-email-kazuhiro.fujita.jg@renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kazuhiro Fujita 2020-03-27 18:17:28 +00:00 committed by Greg Kroah-Hartman
parent 0f87aa66e8
commit 3dc4db3662
1 changed files with 9 additions and 2 deletions
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11
drivers/tty/serial/sh-sci.c
View File

@ -870,9 +870,16 @@ static void sci_receive_chars(struct uart_port *port)
tty_insert_flip_char(tport, c, TTY_NORMAL);
} else {
for (i = 0; i < count; i++) {
char c = serial_port_in(port, SCxRDR);
char c;
status = serial_port_in(port, SCxSR);
if (port->type == PORT_SCIF ||
port->type == PORT_HSCIF) {
status = serial_port_in(port, SCxSR);
c = serial_port_in(port, SCxRDR);
} else {
c = serial_port_in(port, SCxRDR);
status = serial_port_in(port, SCxSR);
}
if (uart_handle_sysrq_char(port, c)) {
count--; i--;
continue;