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serial/imx: check that the buffer is non-empty before sending it out

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The .start_tx callback (imx_start_tx here) isn't only called when the
buffer is non-empty.  E.g. after resume or when handshaking is enabled
and the other side starts to signal being ready.

So check for an empty puffer already before sending the first character.
This prevents sending out stale (or uninitialised) data.

Signed-off-by: Volker Ernst <volker.ernst@txtr.com>
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Andy Green <andy@warmcat.com>
[ukl: reword commit log, put check in while condition]
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Volker Ernst 2010-10-13 11:03:57 +02:00 committed by Greg Kroah-Hartman
parent e5586eccc9
commit 4e4e66029a
1 changed files with 2 additions and 3 deletions
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5
drivers/serial/imx.c
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@ -327,14 +327,13 @@ static inline void imx_transmit_buffer(struct imx_port *sport)
{
struct circ_buf *xmit = &sport->port.state->xmit;
while (!(readl(sport->port.membase + UTS) & UTS_TXFULL)) {
while (!uart_circ_empty(xmit) &&
!(readl(sport->port.membase + UTS) & UTS_TXFULL)) {
/* send xmit->buf[xmit->tail]
* out the port here */
writel(xmit->buf[xmit->tail], sport->port.membase + URTX0);
xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
sport->port.icount.tx++;
if (uart_circ_empty(xmit))
break;
}
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)