Don't take the spinlock and use dev_info_once(). This may cause a hang because the console takes this spinlock, too. Just print this info after we've released the lock. Fixes: 159381df1442f ("tty: serial: fsl_lpuart: fix DMA operation when using IOMMU") Reported-by: Leonard Crestez <leonard.crestez@xxxxxxx> Signed-off-by: Michael Walle <michael@xxxxxxxx> --- drivers/tty/serial/fsl_lpuart.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 9c6a018b1390..960fc2658f19 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1517,9 +1517,6 @@ static void lpuart_tx_dma_startup(struct lpuart_port *sport) sport->dma_tx_chan = dma_request_chan(sport->port.dev, "tx"); if (IS_ERR(sport->dma_tx_chan)) { - dev_info_once(sport->port.dev, - "DMA tx channel request failed, operating without tx DMA (%ld)\n", - PTR_ERR(sport->dma_tx_chan)); sport->dma_tx_chan = NULL; goto err; } @@ -1551,9 +1548,6 @@ static void lpuart_rx_dma_startup(struct lpuart_port *sport) sport->dma_rx_chan = dma_request_chan(sport->port.dev, "rx"); if (IS_ERR(sport->dma_rx_chan)) { - dev_info_once(sport->port.dev, - "DMA rx channel request failed, operating without rx DMA (%ld)\n", - PTR_ERR(sport->dma_rx_chan)); sport->dma_rx_chan = NULL; goto err; } @@ -1601,6 +1595,13 @@ static int lpuart_startup(struct uart_port *port) spin_unlock_irqrestore(&sport->port.lock, flags); + if (!sport->dma_rx_chan) + dev_info_once(sport->port.dev, + "DMA rx channel request failed, operating without rx DMA\n"); + if (!sport->dma_tx_chan) + dev_info_once(sport->port.dev, + "DMA tx channel request failed, operating without tx DMA\n"); + return 0; } @@ -1653,13 +1654,20 @@ static int lpuart32_startup(struct uart_port *port) lpuart32_setup_watermark_enable(sport); - lpuart_rx_dma_startup(sport); lpuart_tx_dma_startup(sport); lpuart32_configure(sport); spin_unlock_irqrestore(&sport->port.lock, flags); + + if (!sport->dma_rx_chan) + dev_info_once(sport->port.dev, + "DMA rx channel request failed, operating without rx DMA\n"); + if (!sport->dma_tx_chan) + dev_info_once(sport->port.dev, + "DMA tx channel request failed, operating without tx DMA\n"); + return 0; } -- 2.20.1