It needed an explanation.
Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_dw.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 1ca7d75..cf405ad 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -247,7 +247,15 @@ out:
serial8250_do_set_termios(p, termios, old);
}
-static bool dw8250_dma_filter(struct dma_chan *chan, void *param)
+/*
+ * dw8250_fallback_dma_filter will prevent the UART from getting just any free
+ * channel on platforms that have DMA engines, but don't have any channels
+ * assigned to the UART.
+ *
+ * REVISIT: This is a work around for limitation in the DMA Engine API. Once the
+ * core problem is fixed, this function is no longer needed.
+ */
+static bool dw8250_fallback_dma_filter(struct dma_chan *chan, void *param)
{
return false;
}
@@ -382,6 +390,7 @@ static int dw8250_probe(struct platform_device *pdev)
if (!data)
return -ENOMEM;
+ data->dma.fn = dw8250_fallback_dma_filter;
data->usr_reg = DW_UART_USR;
p->private_data = data;
@@ -468,10 +477,6 @@ static int dw8250_probe(struct platform_device *pdev)
if (!IS_ERR(data->rst))
reset_control_deassert(data->rst);
- data->dma.rx_param = data;
- data->dma.tx_param = data;
- data->dma.fn = dw8250_dma_filter;
-
dw8250_quirks(p, data);
/* If the Busy Functionality is not implemented, don't handle it */
--
2.5.1
--
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