From: Vignesh R Date: Fri, 20 Jan 2017 08:16:52 +0000 (+0530) Subject: serial: 8250_omap: pause DMA only if DMA transfer in progress X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=75f54acc086940ccef8b6d67ba8537529bda104c;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git serial: 8250_omap: pause DMA only if DMA transfer in progress 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 Acked-by: Tony Lindgren Signed-off-by: Greg Kroah-Hartman --- 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);