linux-kernel - [PATCH] [bfin-sport-uart] The waiting loop to stop SPORT TX from TX interrupt is too long

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Date:	Mon, 21 Sep 2009 19:02:53 +0800
From:	sonic zhang <sonic.adi@...il.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linux Serial <linux-serial@...r.kernel.org>
Subject: [PATCH] [bfin-sport-uart] The waiting loop to stop SPORT TX from
	TX interrupt is too long

The waiting loop to stop SPORT TX from TX interrupt is
too long. This may block SPORT RX interrupts and cause
RX FIFO overflow. So, do stop sport TX only after the last
char in TX FIFO is moved into the shift register.


Signed-off-by: Sonic Zhang <sonic.zhang@...log.com>
---
 drivers/serial/bfin_sport_uart.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/drivers/serial/bfin_sport_uart.c b/drivers/serial/bfin_sport_uart.c
index c108b1a..fb9f7cd 100644
--- a/drivers/serial/bfin_sport_uart.c
+++ b/drivers/serial/bfin_sport_uart.c
@@ -303,7 +303,13 @@ static void sport_uart_tx_chars(struct sport_uart_port *up)
 	}
 
 	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
-		sport_stop_tx(&up->port);
+		/* The waiting loop to stop SPORT TX from TX interrupt is
+		 * too long. This may block SPORT RX interrupts and cause
+		 * RX FIFO overflow. So, do stop sport TX only after the last
+		 * char in TX FIFO is moved into the shift register.
+		 */
+		if (SPORT_GET_STAT(up) & TXHRE)
+			sport_stop_tx(&up->port);
 		return;
 	}
 
-- 
1.6.0



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