于 2013年07月16日 17:54, Uwe Kleine-König 写道:
On Tue, Jul 16, 2013 at 02:55:31PM +0800, Huang Shijie wrote:
The original DMA support works only when RTS/CTS is enabled.
What is original here?
i will add more information for this in the next version.
But after several patches, DMA support has lost this limit.
This is still misleading.
This patch adds an optional property for the UART DT node
which indicates the UART has RTS and CTS lines.
This patch also adds a macro MXS_AUART_RTSCTS, and uses it to check
RTS/CTS before we enable the DMA for the UART.
I still think this should go to stable. The options are:
a) also take patch 1 into stable
b) apply this patch without patch 1
I don't know if option a) is OK, b) is probably preferable. And as Greg
to Greg:
I think a) is ok to me. what's your opinion?
has much to do anyhow, better move this patch first. (Otherwise he will
probably only say: That patch doesn't apply, please help.)
Signed-off-by: Huang Shijie<b32955@xxxxxxxxxxxxx>
---
.../bindings/tty/serial/fsl-mxs-auart.txt | 4 ++++
drivers/tty/serial/mxs-auart.c | 5 ++++-
2 files changed, 8 insertions(+), 1 deletions(-)
diff --git a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
index 2c00ec6..59a40f1 100644
--- a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
+++ b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
@@ -10,6 +10,10 @@ Required properties:
Refer to dma.txt and fsl-mxs-dma.txt for details.
- dma-names: "rx" for RX channel, "tx" for TX channel.
+Optional properties:
+- fsl,uart-has-rtscts : Indicate the UART has RTS and CTS lines,
+ it also means you enable the DMA support for this UART.
+
Example:
auart0: serial@8006a000 {
compatible = "fsl,imx28-auart", "fsl,imx23-auart";
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 465ef0b..27532fd 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -134,6 +134,7 @@ enum mxs_auart_type {
struct mxs_auart_port {
struct uart_port port;
+#define MXS_AUART_RTSCTS 1
#define MXS_AUART_DMA_ENABLED 0x2
#define MXS_AUART_DMA_TX_SYNC 2 /* bit 2 */
#define MXS_AUART_DMA_RX_READY 3 /* bit 3 */
@@ -639,7 +640,7 @@ static void mxs_auart_settermios(struct uart_port *u,
* we can only implement the DMA support for auart
* in mx28.
*/
- if (is_imx28_auart(s)) {
+ if (is_imx28_auart(s)&& (s->flags& MXS_AUART_RTSCTS)) {
I thought you wanted to add a comment here. Without knowing the details
if (RTSCTS)
enable_dma();
ok, no problem.
thanks
Huang Shijie
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