UARTs which do not trigger THRE interrupt if the fifo is already
empty when the interrupt is enabled need tx primed manually. These
UARTs are identified by the UART_BUG_TXEN flag to enable the
required workaround.
However, the current workaround is broken; if the fifo is already
empty but the shifter is still transmitting, then serial8250_tx_chars()
will not be called but no further THRE interrupt will occur, and
tx will stall. The appropriate check is for fifo empty (THRE), not
transmitter empty (TEMT).
Signed-off-by: Dick Hollenbeck <[email protected]>
[pjh: rewrote commit log]
Signed-off-by: Peter Hurley <[email protected]>
---
drivers/tty/serial/8250/8250_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 285694b..0c61a9b 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1365,7 +1365,7 @@ static void serial8250_start_tx(struct uart_port *port)
unsigned char lsr;
lsr = serial_in(up, UART_LSR);
up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
- if (lsr & UART_LSR_TEMT)
+ if (lsr & UART_LSR_THRE)
serial8250_tx_chars(up);
}
}
--
2.2.2