serial/imx: check that the buffer is non-empty before sending it out (4e4e6602) · Commits · 戴 / test

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>

drivers/serial/imx.c

+2 −3

Original line number	Original line	Diff line number	Diff line
	@@ -327,14 +327,13 @@ static inline void imx_transmit_buffer(struct imx_port *sport)
	{		{
	struct circ_buf *xmit = &sport->port.state->xmit;		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]		/* send xmit->buf[xmit->tail]
	* out the port here */		* out the port here */
	writel(xmit->buf[xmit->tail], sport->port.membase + URTX0);		writel(xmit->buf[xmit->tail], sport->port.membase + URTX0);
	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
	sport->port.icount.tx++;		sport->port.icount.tx++;
	if (uart_circ_empty(xmit))
	break;
	}		}

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)

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