@@ -2416,6 +2416,7 @@ static int lpuart_probe(struct platform_device *pdev)
const struct lpuart_soc_data *sdata = of_id->data;
struct device_node *np = pdev->dev.of_node;
struct lpuart_port *sport;
+ struct dma_chan *dma_chan;
struct resource *res;
int ret;
@@ -2483,6 +2484,26 @@ static int lpuart_probe(struct platform_device *pdev)
}
sport->port.line = ret;
+ dma_chan = dma_request_chan(sport->port.dev, "tx");
+ if (PTR_ERR(dma_chan) == -EPROBE_DEFER) {
+ ret = -EPROBE_DEFER;
+ goto failed_request_tx_dma;
+ } else if (IS_ERR(dma_chan))
+ dev_info(sport->port.dev, "DMA tx channel request failed, "
+ "operating without tx DMA\n");
+ else
+ sport->dma_tx_chan = dma_chan;
+
+ dma_chan = dma_request_chan(sport->port.dev, "rx");
+ if (PTR_ERR(dma_chan) == -EPROBE_DEFER) {
+ ret = -EPROBE_DEFER;
+ goto failed_request_rx_dma;
+ } else if (IS_ERR(dma_chan))
+ dev_info(sport->port.dev, "DMA rx channel request failed, "
+ "operating without rx DMA\n");
+ else
+ sport->dma_rx_chan = dma_chan;
+
ret = lpuart_enable_clks(sport);
if (ret)
goto failed_clock_enable;
@@ -2520,22 +2541,16 @@ static int lpuart_probe(struct platform_device *pdev)
sport->port.rs485_config(&sport->port, &sport->port.rs485);
- sport->dma_tx_chan = dma_request_slave_channel(sport->port.dev, "tx");
- if (!sport->dma_tx_chan)
- dev_info(sport->port.dev, "DMA tx channel request failed, "
- "operating without tx DMA\n");
-
- sport->dma_rx_chan = dma_request_slave_channel(sport->port.dev, "rx");
- if (!sport->dma_rx_chan)
- dev_info(sport->port.dev, "DMA rx channel request failed, "
- "operating without rx DMA\n");
-
return 0;
failed_attach_port:
failed_irq_request:
lpuart_disable_clks(sport);
failed_clock_enable:
+ dma_release_channel(sport->dma_rx_chan);
+failed_request_rx_dma:
+ dma_release_channel(sport->dma_tx_chan);
+failed_request_tx_dma:
failed_out_of_range:
if (sport->id_allocated)
ida_simple_remove(&fsl_lpuart_ida, sport->port.line);
The DMA channel might not be available at the first probe time. This is esp. the case if the DMA controller has an IOMMU mapping. Use the new dma_request_chan() API and handle EPROBE_DEFER errors. Also reorder the code a bit, so that we don't prepare the whole UART just to determine that the DMA channel is not ready yet and we have to undo all the stuff. Try to map the DMA channels earlier. Signed-off-by: Michael Walle <michael@walle.cc> --- drivers/tty/serial/fsl_lpuart.c | 35 +++++++++++++++++++++++---------- 1 file changed, 25 insertions(+), 10 deletions(-)