The serial core expects the UART driver to transmit x_char
(START/STOP chars) even if tx is stopped and before data already
in the tx ring buffer if possible. Also, sending x_char must
not cause additional data in the tx ring buffer to transmit
if tx is stopped.
Cause x_char to be transmitted before any other data is sent.
Auto-stop tx if the tx ring buffer is empty or tx should be stopped.
Only perform one write wakeup if tx ring buffer space is below
threshold.
x_char handling in DMA mode is still broken; add FIXME.
Signed-off-by: Peter Hurley <pe...@hurleysoftware.com>
---
drivers/tty/serial/imx.c | 39 ++++++++++++++++-----------------------
1 file changed, 16 insertions(+), 23 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 044e86d..c86f153 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -464,9 +464,19 @@ static inline void imx_transmit_buffer(struct imx_port
*sport)
{
struct circ_buf *xmit = &sport->port.state->xmit;
+ if (sport->port.x_char) {
+ /* Send next char */
+ writel(sport->port.x_char, sport->port.membase + URTX0);
+ return;
+ }
+
+ if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
+ imx_stop_tx(&sport->port);
+ return;
+ }
+
while (!uart_circ_empty(xmit) &&
- !(readl(sport->port.membase + uts_reg(sport))
- & UTS_TXFULL)) {
+ !(readl(sport->port.membase + uts_reg(sport)) & UTS_TXFULL)) {
/* send xmit->buf[xmit->tail]
* out the port here */
writel(xmit->buf[xmit->tail], sport->port.membase + URTX0);
@@ -567,9 +577,6 @@ static void imx_start_tx(struct uart_port *port)
struct imx_port *sport = (struct imx_port *)port;
unsigned long temp;
- if (uart_circ_empty(&port->state->xmit))
- return;
-
if (USE_IRDA(sport)) {
/* half duplex in IrDA mode; have to disable receive mode */
temp = readl(sport->port.membase + UCR4);
@@ -604,7 +611,10 @@ static void imx_start_tx(struct uart_port *port)
}
if (sport->dma_is_enabled) {
- imx_dma_tx(sport);
+ /* FIXME: port->x_char must be transmitted if != 0 */
+ if (!uart_circ_empty(&port->state->xmit) &&
+ !uart_tx_stopped(port))
+ imx_dma_tx(sport);
return;
}
@@ -632,27 +642,10 @@ static irqreturn_t imx_rtsint(int irq, void *dev_id)
static irqreturn_t imx_txint(int irq, void *dev_id)
{
struct imx_port *sport = dev_id;
- struct circ_buf *xmit = &sport->port.state->xmit;
unsigned long flags;
spin_lock_irqsave(&sport->port.lock, flags);
- if (sport->port.x_char) {
- /* Send next char */
- writel(sport->port.x_char, sport->port.membase + URTX0);
- goto out;
- }
-
- if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
- imx_stop_tx(&sport->port);
- goto out;
- }
-
imx_transmit_buffer(sport);
-
- if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
- uart_write_wakeup(&sport->port);
-
-out:
spin_unlock_irqrestore(&sport->port.lock, flags);
return IRQ_HANDLED;
}
--
2.1.0
--
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