[PATCH] tty: serial: fsl_lpuart: Fix Tx DMA edge case
From: stefan@agner.ch (Stefan Agner)
Date: 2016-10-07 18:12:29
Also in:
linux-serial, lkml
On 2016-10-06 15:13, Aaron Brice wrote:
In the case where head == 0 on the circular buffer, there should be one DMA buffer, not two. The second zero-length buffer would break the lpuart driver, transfer would never complete.
That looks right, and seems to work fine here: Acked-by: Stefan Agner <stefan@agner.ch> Tested-by: Stefan Agner <stefan@agner.ch> @Greg, would be good if this would still make it into 4.9. -- Stefan
quoted hunk ↗ jump to hunk
Signed-off-by: Aaron Brice <redacted> --- drivers/tty/serial/fsl_lpuart.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index de9d510..76103f2 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c@@ -328,7 +328,7 @@ static void lpuart_dma_tx(struct lpuart_port *sport) sport->dma_tx_bytes = uart_circ_chars_pending(xmit); - if (xmit->tail < xmit->head) { + if (xmit->tail < xmit->head || xmit->head == 0) { sport->dma_tx_nents = 1; sg_init_one(sgl, xmit->buf + xmit->tail, sport->dma_tx_bytes); } else {@@ -359,7 +359,6 @@ static void lpuart_dma_tx(struct lpuart_port *sport) sport->dma_tx_in_progress = true; sport->dma_tx_cookie = dmaengine_submit(sport->dma_tx_desc); dma_async_issue_pending(sport->dma_tx_chan); - } static void lpuart_dma_tx_complete(void *arg)