[PATCH LINUX v3 03/10] tty: xuartps: Don't consider circular buffer when enabling transmitter
From: Soren Brinkmann <hidden>
Date: 2015-11-22 03:01:12
Also in:
linux-serial, lkml
Subsystem:
the rest, tty layer and serial drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
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 <redacted> Signed-off-by: Soren Brinkmann <redacted> --- 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