-----Original Message-----
From: Thierry Reding <redacted>
Sent: Tuesday, August 13, 2019 3:19 PM
To: Krishna Yarlagadda <redacted>
Cc: gregkh@linuxfoundation.org; robh+dt@kernel.org;
mark.rutland@arm.com; Jonathan Hunter [off-list ref]; Laxman
Dewangan [off-list ref]; jslaby@suse.com; linux-
serial@vger.kernel.org; devicetree@vger.kernel.org; linux-
tegra@vger.kernel.org; linux-kernel@vger.kernel.org; Shardar Mohammed
[off-list ref]
Subject: Re: [PATCH 05/14] serial: tegra: flush the RX fifo on frame error

On Mon, Aug 12, 2019 at 04:58:14PM +0530, Krishna Yarlagadda wrote:

quoted

From: Shardar Shariff Md <redacted>

FIFO reset/flush code implemented now does not follow programming
guidelines. RTS line has to be turned off while flushing fifos to
avoid new transfers. Also check LSR bits UART_LSR_TEMT and

UART_LSR_DR

quoted

to confirm fifos are flushed.

You use inconsistent spelling for FIFO here.

Will fix in next version and take care of this in all patches

quoted

Signed-off-by: Shardar Shariff Md <redacted>
Signed-off-by: Krishna Yarlagadda <redacted>
---
 drivers/tty/serial/serial-tegra.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/tty/serial/serial-tegra.c

b/drivers/tty/serial/serial-tegra.c
index ae7225c..f6a3f4e 100644

--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c

@@ -266,6 +266,10 @@ static void tegra_uart_wait_sym_time(struct

tegra_uart_port *tup,  static void tegra_uart_fifo_reset(struct
tegra_uart_port *tup, u8 fcr_bits)  {
 	unsigned long fcr = tup->fcr_shadow;
+	unsigned int lsr, tmout = 10000;
+
+	if (tup->rts_active)
+		set_rts(tup, false);

 	if (tup->cdata->allow_txfifo_reset_fifo_mode) {
 		fcr |= fcr_bits & (UART_FCR_CLEAR_RCVR |

UART_FCR_CLEAR_XMIT); @@

quoted

-289,6 +293,17 @@ static void tegra_uart_fifo_reset(struct tegra_uart_port

*tup, u8 fcr_bits)

quoted

 	 * to propagate, otherwise data could be lost.
 	 */
 	tegra_uart_wait_cycle_time(tup, 32);
+
+	do {
+		lsr = tegra_uart_read(tup, UART_LSR);
+		if (lsr | UART_LSR_TEMT)
+			if (!(lsr & UART_LSR_DR))

Can't both of these go on the same line?

Thierry

They can be. Will fix in next version
KY

quoted

+				break;
+		udelay(1);
+	} while (--tmout);
+
+	if (tup->rts_active)
+		set_rts(tup, true);
 }

 static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned
int baud)
--
2.7.4