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[PATCH LINUX v3 03/10] tty: xuartps: Don't consider circular buffer when enabling transmitter

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Restarting the transmitter even if the circ buffer is empty may be
necessary to push out remaining data when the port is restarted after
being stopped.

Cc: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
v3:
 - changed this patch to not always enable the transmitter, but keep the
   check for uart_tx_stopped() in place, as suggested by Peter, whose
   explanation I also stole for the new commit message (thx)
---
 drivers/tty/serial/xilinx_uartps.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 2c98c357d9a0..6a7cd4e057ae 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -512,7 +512,7 @@ static void cdns_uart_start_tx(struct uart_port *port)
 {
 	unsigned int status, numbytes = port->fifosize;
 
-	if (uart_circ_empty(&port->state->xmit) || uart_tx_stopped(port))
+	if (uart_tx_stopped(port))
 		return;
 
 	/*
@@ -524,6 +524,9 @@ static void cdns_uart_start_tx(struct uart_port *port)
 	status |= CDNS_UART_CR_TX_EN;
 	writel(status, port->membase + CDNS_UART_CR_OFFSET);
 
+	if (uart_circ_empty(&port->state->xmit))
+		return;
+
 	while (numbytes-- && ((readl(port->membase + CDNS_UART_SR_OFFSET) &
 				CDNS_UART_SR_TXFULL)) != CDNS_UART_SR_TXFULL) {
 		/* Break if no more data available in the UART buffer */
-- 
2.6.3.3.g9bb996a

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[PATCH LINUX v3 00/10] tty: xuartps: Fix lock ups Soren Brinkmann <soren.brinkmann@xilinx.com> - 2015-11-22 04:00 +0100
  [PATCH LINUX v3 07/10] tty: xuartps: Acquire port lock for shutdown Soren Brinkmann <soren.brinkmann@xilinx.com> - 2015-11-22 04:00 +0100
  [PATCH LINUX v3 01/10] tty: xuartps: Beautify read-modify writes Soren Brinkmann <soren.brinkmann@xilinx.com> - 2015-11-22 04:10 +0100
  [PATCH LINUX v3 09/10] tty: xuartps: Only handle RX IRQs when RX is enabled Soren Brinkmann <soren.brinkmann@xilinx.com> - 2015-11-22 04:10 +0100
  [PATCH LINUX v3 03/10] tty: xuartps: Don't consider circular buffer when enabling transmitter Soren Brinkmann <soren.brinkmann@xilinx.com> - 2015-11-22 04:10 +0100
  [PATCH LINUX v3 04/10] tty: xuartps: Clear interrupt status register in shutdown Soren Brinkmann <soren.brinkmann@xilinx.com> - 2015-11-22 04:10 +0100
  [PATCH LINUX v3 05/10] tty: xuartps: Improve startup function Soren Brinkmann <soren.brinkmann@xilinx.com> - 2015-11-22 04:10 +0100

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