[PATH RESEND v2 03/10] tty: xuartps: Always enable transmitter in start_tx
From: Peter Hurley <hidden>
Date: 2015-11-19 23:15:09
On 11/19/2015 03:02 PM, Soren Brinkmann wrote:
start_tx must start transmitting characters. Regardless of the state of the circular buffer, always enable the transmitter hardware.
Why? Does cdns_uart_stop_tx() actually stop the transmitter so that data is remains in the transmitter?
quoted hunk ↗ jump to hunk
Signed-off-by: Soren Brinkmann <redacted> --- drivers/tty/serial/xilinx_uartps.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index 2c98c357d9a0..df6778d17949 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c@@ -512,9 +512,6 @@ 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)) - return;
The test for tx stopped needs to remain; otherwise, transmission will restart even if the tty has been stopped (for example by userspace) or IXON software flow control. Regards, Peter Hurley
quoted hunk ↗ jump to hunk
- /* * Set the TX enable bit and clear the TX disable bit to enable the * transmitter.@@ -524,6 +521,9 @@ 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) || uart_tx_stopped(port)) + 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 */