@@ -112,6 +112,7 @@ 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)
@@ -773,6 +774,7 @@ 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;
unsigned long flags;
+ int ret;
spin_lock_irqsave(&priv->rx_dma_lock, flags);
@@ -781,7 +783,9 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p)
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);
@@ -825,6 +829,9 @@ static int omap_8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
break;
}
+ if (priv->rx_dma_broken)
+ return -EINVAL;
+
spin_lock_irqsave(&priv->rx_dma_lock, flags);
if (dma->rx_running)
@@ -1219,6 +1226,11 @@ static int omap8250_probe(struct platform_device *pdev)
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
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. Cc: <stable@vger.kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- v1…v2: - disable RX-DMA right on boot drivers/tty/serial/8250/8250_omap.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)