From mboxrd@z Thu Jan 1 00:00:00 1970 From: u.kleine-koenig@pengutronix.de (=?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?=) Date: Wed, 13 Oct 2010 11:03:57 +0200 Subject: [PATCH] serial/imx: check that the buffer is non-empty before sending it out In-Reply-To: <20101008091640.GD29673@pengutronix.de> References: <20101008091640.GD29673@pengutronix.de> Message-ID: <1286960637-11600-1-git-send-email-u.kleine-koenig@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Volker Ernst 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 Signed-off-by: Daniel Mack Cc: Andy Green [ukl: reword commit log, put check in while condition] Signed-off-by: Uwe Kleine-K?nig --- Hello, as I didn't sent a patch, here comes my current version. Don't know if it makes it easier to test for you ... I faked Daniel's SoB as Andrew said he did, compressed the changelog a bit and put the check in the while condition as I suggested. Best regards Uwe drivers/serial/imx.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c index 66ecc7a..dfcf4b1 100644 --- a/drivers/serial/imx.c +++ b/drivers/serial/imx.c @@ -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) -- 1.7.2.3