[PATCH 05/14] serial: tegra: flush the RX fifo on frame error
From: Krishna Yarlagadda <hidden>
Date: 2019-08-12 11:28:59
Also in:
linux-serial, linux-tegra, lkml
Subsystem:
tegra serial driver, the rest, tty layer and serial drivers · Maintainers:
Laxman Dewangan, Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
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 to confirm fifos are flushed. 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);
@@ -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