For dm uarts in pio mode tx data is transferred to the fifo register 4 bytes at a time, but care is not taken when these 4 bytes spans the end of the xmit buffer so the loop might read up to 3 bytes past the buffer and then skip the actual data at the beginning of the buffer. Fix this by, analogous to the DMA case, make sure the chunk doesn't wrap the xmit buffer. Fixes: 3a878c430fd6 ("tty: serial: msm: Add TX DMA support") Cc: Andy Gross <andy.gross@xxxxxxxxxx> Cc: Ivan Ivanov <iivanov.xz@xxxxxxxxx> Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Reported-by: Frank Rowand <frowand.list@xxxxxxxxx> Reported-by: Nicolas Dechesne <nicolas.dechesne@xxxxxxxxxx> Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx> --- drivers/tty/serial/msm_serial.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index b7d80bd57db9..7d62610d9de5 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -726,7 +726,7 @@ static void msm_handle_tx(struct uart_port *port) return; } - pio_count = CIRC_CNT(xmit->head, xmit->tail, UART_XMIT_SIZE); + pio_count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE); dma_count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE); dma_min = 1; /* Always DMA */ -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html