From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vignesh R Subject: [PATCH 1/3] serial: 8250: omap: pause DMA only if DMA transfer in progress Date: Fri, 13 Jan 2017 13:31:59 +0530 Message-ID: <20170113080201.6515-2-vigneshr@ti.com> References: <20170113080201.6515-1-vigneshr@ti.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <20170113080201.6515-1-vigneshr@ti.com> Sender: linux-kernel-owner@vger.kernel.org To: Greg Kroah-Hartman Cc: Jiri Slaby , Peter Hurley , Sebastian Andrzej Siewior , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, Vignesh R List-Id: linux-serial@vger.kernel.org It is possible that DMA transfer is already complete but, completion handler is yet to be called, when dmaengine_pause() is called in case of error condition(like break/rx timeout). This leads to dmaengine_pause() API to return EINVAL (as descriptor is already NULL) causing rx_dma_broken flag to be set and effectively disabling RX DMA. Fix this by calling dmaengine_pause() only when transfer is in progress. Signed-off-by: Vignesh R --- drivers/tty/serial/8250/8250_omap.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index 61ad6c3b20a0..4ad1934ef6ed 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -790,6 +790,7 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p) { struct omap8250_priv *priv = p->port.private_data; struct uart_8250_dma *dma = p->dma; + struct dma_tx_state state; unsigned long flags; int ret; @@ -800,10 +801,12 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p) return; } - ret = dmaengine_pause(dma->rxchan); - if (WARN_ON_ONCE(ret)) - priv->rx_dma_broken = true; - + ret = dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state); + if (ret == DMA_IN_PROGRESS) { + ret = dmaengine_pause(dma->rxchan); + if (WARN_ON_ONCE(ret)) + priv->rx_dma_broken = true; + } spin_unlock_irqrestore(&priv->rx_dma_lock, flags); __dma_rx_do_complete(p); -- 2.11.0