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[v2,3/4] serial: sh-sci: Clear RX, error, and break flags during reset

Message ID 1466780356-12623-4-git-send-email-geert+renesas@glider.be (mailing list archive)
State Accepted
Delegated to: Geert Uytterhoeven
Headers show

Commit Message

Geert Uytterhoeven June 24, 2016, 2:59 p.m. UTC
Setting the FIFO reset bits is not sufficient to reset the RX FIFO.
After this the status register's RDF flag bit may still be set, causing
the reception of one stale byte of data.

To fix this, clear all status flag bits related to reception, error, and
break handling, cfr. the initialization flowchart in the datasheet.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v2:
  - No changes.
---
 drivers/tty/serial/sh-sci.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox

Patch

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index eecace576c3b758f..0a2be5d293220e08 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -2055,6 +2055,10 @@  static void sci_reset(struct uart_port *port)
 	reg = sci_getreg(port, SCFCR);
 	if (reg->size)
 		serial_port_out(port, SCFCR, SCFCR_RFRST | SCFCR_TFRST);
+
+	sci_clear_SCxSR(port,
+			SCxSR_RDxF_CLEAR(port) & SCxSR_ERROR_CLEAR(port) &
+			SCxSR_BREAK_CLEAR(port));
 }
 
 static void sci_set_termios(struct uart_port *port, struct ktermios *termios,