[linux-yocto] [PATCH 12/18] serial: 8250_dw: rename and comment the fallback dma filter

[Tan Jui Nee]

From: Heikki Krogerus <heikki.krogerus at linux.intel.com>

Adding comment where the purpose of the function is
explained.

The dma parameters are not used, so removing them, and also
moving the assignment of the function to the same place
where the other dw8250_data structures members are being set
in dw8250_probe.

Signed-off-by: Heikki Krogerus <heikki.krogerus at linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry picked from commit 1edb3cf21f4b0be2a5d9577d4913eb9a3131cd16)
Signed-off-by: Tan Jui Nee <jui.nee.tan at intel.com>
---
 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 a4aa671..a16579e 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -243,7 +243,15 @@ 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;
 }
@@ -370,6 +378,7 @@ 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;
 
@@ -456,10 +465,6 @@ 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 */
-- 
1.9.1