4.2-stable review patch. If anyone has any objections, please let me know.
------------------ From: Sebastian Andrzej Siewior <[email protected]> commit 830acf9e3044d4644f91b4418ef35a2094089946 upstream. The 8250-omap driver requires the DMA-engine driver to support the pause command in order to properly turn off programmed RX transfer before the driver stars manually reading from the FIFO. The lacking support of the requirement has been discovered recently. In order to stay safe here we disable RX-DMA completly on probe. The rx_dma_broken assignment on probe could be removed once we working pause function in omap-dma. Signed-off-by: Sebastian Andrzej Siewior <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/tty/serial/8250/8250_omap.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -100,6 +100,7 @@ struct omap8250_priv { struct work_struct qos_work; struct uart_8250_dma omap8250_dma; spinlock_t rx_dma_lock; + bool rx_dma_broken; }; static u32 uart_read(struct uart_8250_port *up, u32 reg) @@ -754,6 +755,7 @@ static void omap_8250_rx_dma_flush(struc struct omap8250_priv *priv = p->port.private_data; struct uart_8250_dma *dma = p->dma; unsigned long flags; + int ret; spin_lock_irqsave(&priv->rx_dma_lock, flags); @@ -762,7 +764,9 @@ static void omap_8250_rx_dma_flush(struc return; } - dmaengine_pause(dma->rxchan); + ret = dmaengine_pause(dma->rxchan); + if (WARN_ON_ONCE(ret)) + priv->rx_dma_broken = true; spin_unlock_irqrestore(&priv->rx_dma_lock, flags); @@ -806,6 +810,9 @@ static int omap_8250_rx_dma(struct uart_ break; } + if (priv->rx_dma_broken) + return -EINVAL; + spin_lock_irqsave(&priv->rx_dma_lock, flags); if (dma->rx_running) @@ -1180,6 +1187,11 @@ static int omap8250_probe(struct platfor if (of_machine_is_compatible("ti,am33xx")) priv->habit |= OMAP_DMA_TX_KICK; + /* + * pause is currently not supported atleast on omap-sdma + * and edma on most earlier kernels. + */ + priv->rx_dma_broken = true; } } #endif -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
