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Subject[PATCH 05/14] serial: tegra: flush the RX fifo on frame error
Date
From: Shardar Shariff Md <smohammed@nvidia.com>

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
to confirm fifos are flushed.

Signed-off-by: Shardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
---
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);
@@ -289,6 +293,17 @@ static void tegra_uart_fifo_reset(struct tegra_uart_port *tup, u8 fcr_bits)
* 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))
+ 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
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