From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Dooks Subject: [PATCH 3/9] ARM: meson: serial: tx_empty fails to check for transmitter busy Date: Wed, 18 Nov 2015 14:41:13 +0000 Message-ID: <1447857679-30158-4-git-send-email-ben.dooks@codethink.co.uk> References: <1447857679-30158-1-git-send-email-ben.dooks@codethink.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1447857679-30158-1-git-send-email-ben.dooks@codethink.co.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: edward.cragg@codethink.co.uk Cc: Greg Kroah-Hartman , linux-meson@googlegroups.com, linux-kernel@codethink.co.uk, Ben Dooks , linux-serial@vger.kernel.org, Jiri Slaby , carlo@caione.org, linux-arm-kernel@lists.infradead.org List-Id: linux-serial@vger.kernel.org The tx_empty() uart_op should only return empty if both the transmit fifo and the transmit state-machine are both idle. Add a test for the hardware's XMIT_BUSY flag. Note, this is possibly related to an issue where the port is being shutdown with paritally transmitted characters in it. Signed-off-by: Ben Dooks Reported-by: Edward Cragg --- drivers/tty/serial/meson_uart.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c index b87eb97..54d1b95 100644 --- a/drivers/tty/serial/meson_uart.c +++ b/drivers/tty/serial/meson_uart.c @@ -57,6 +57,7 @@ #define AML_UART_RX_EMPTY BIT(20) #define AML_UART_TX_FULL BIT(21) #define AML_UART_TX_EMPTY BIT(22) +#define AML_UART_XMIT_BUSY BIT(25) #define AML_UART_ERR (AML_UART_PARITY_ERR | \ AML_UART_FRAME_ERR | \ AML_UART_TX_FIFO_WERR) @@ -100,7 +101,8 @@ static unsigned int meson_uart_tx_empty(struct uart_port *port) u32 val; val = readl(port->membase + AML_UART_STATUS); - return (val & AML_UART_TX_EMPTY) ? TIOCSER_TEMT : 0; + val &= (AML_UART_TX_EMPTY | AML_UART_XMIT_BUSY); + return (val == AML_UART_TX_EMPTY) ? TIOCSER_TEMT : 0; } static void meson_uart_stop_tx(struct uart_port *port) -- 2.6.2