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[2/5] serial: sh: Improve FIFO empty check on RX

Message ID 20200509203802.821856-2-marek.vasut+renesas@gmail.com
State New
Delegated to: Marek Vasut
Headers show
Series [1/5] sh: Set gd->malloc_base if MALLOC_F_LEN is set | expand

Commit Message

Marek Vasut May 9, 2020, 8:37 p.m. UTC
If the SCIF is receiving data quickly enough, it may happen that the
SCxSR_RDxF flag is cleared in sh_serial_getc_generic(), while the
FIFO still contains data. If that happens, the serial_getc_check()
reports no data in the FIFO as the flag is no longer set. Add one
more check, if the SCxSR_RDxF is not set, read out the FIFO level
and if there are still characters in the FIFO, permit reading them

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
 drivers/serial/serial_sh.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
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diff --git a/drivers/serial/serial_sh.c b/drivers/serial/serial_sh.c
index acfcc2954a..0a4dfdc377 100644
--- a/drivers/serial/serial_sh.c
+++ b/drivers/serial/serial_sh.c
@@ -115,7 +115,10 @@  static int serial_getc_check(struct uart_port *port)
 	if (sci_in(port, SCLSR) & SCxSR_ORER(port))
-	return status & (SCIF_DR | SCxSR_RDxF(port));
+	status &= (SCIF_DR | SCxSR_RDxF(port));
+	if (status)
+		return status;
+	return scif_rxfill(port);
 static int sh_serial_getc_generic(struct uart_port *port)