[PATCH v3 0/3] serial: mxs-auart: add RTS/CTS check for DMA support

[PATCH v3 0/3] serial: mxs-auart: add RTS/CTS check for DMA support

[Huang Shijie]

The original DMA support works only when RTS/CTS is enabled.
(see the "e800163 serial: mxs-auart: add the DMA support for mx28")
But after several patches, DMA support has lost this limit.
(see the "bcc20f9 serial: mxs-auart: move to use generic DMA helper")

So a UART without the RTS/CTS lines may also enables the DMA support
for it, but it may does not work or works abnormally (since without the
RTS/CTS signals, the TX/RX may not works)		

This patch set remove the unnecessary macro MXS_AUART_DMA_CONFIG,
and adds an optional property "fsl,uart-has-rtscts" for the UART DT node
which indicates the UART has RTS and CTS lines.

This patch set also adds a macro MXS_AUART_RTSCTS, and uses it to check
RTS/CTS before we enable the DMA for the UART.

At last, enable the DMA support for auart0 in the imx28-evk boards.

v2 --> v3:
	[0] make the patch 2 as the first patch.
	[1] add more comments.

v1 --> v2:
	[0] changed the comments.
	[1] fix the typos.

Huang Shijie (3):
  serial: mxs: enable the DMA only when the RTS/CTS is valid
  serial: mxs: remove the MXS_AUART_DMA_CONFIG
  ARM: dts: imx28-evk: add the RTS/CTS property for auart0

 .../bindings/tty/serial/fsl-mxs-auart.txt          |    4 ++++
 arch/arm/boot/dts/imx28-evk.dts                    |    1 +
 drivers/tty/serial/mxs-auart.c                     |    8 +++++---
 3 files changed, 10 insertions(+), 3 deletions(-)

-- 
1.7.4.4

[PATCH v3 1/3] serial: mxs: enable the DMA only when the RTS/CTS is valid

[Huang Shijie]

From: Huang Shijie <b32955@freescale.com>

The original DMA support works only when RTS/CTS is enabled.
(see the "e800163 serial: mxs-auart: add the DMA support for mx28")
But after several patches, DMA support has lost this limit.
(see the "bcc20f9 serial: mxs-auart: move to use generic DMA helper")

So an UART without the RTS/CTS lines may also enables the DMA support,
in which case the UART may gets unpredictable results.

This patch adds an optional property for the UART DT node
which indicates the UART has RTS and CTS lines, and it also means you
enable the DMA support for this UART.

This patch also adds a macro MXS_AUART_RTSCTS, and uses it to check
RTS/CTS before we enable the DMA for the UART.

Cc: stable at vger.kernel.org
Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Huang Shijie <shijie8@gmail.com>
---
 .../bindings/tty/serial/fsl-mxs-auart.txt          |    4 ++++
 drivers/tty/serial/mxs-auart.c                     |    7 ++++++-
 2 files changed, 10 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 at 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 736e95c..eac7b58 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -137,6 +137,7 @@ struct mxs_auart_port {
 #define MXS_AUART_DMA_ENABLED	0x2
 #define MXS_AUART_DMA_TX_SYNC	2  /* bit 2 */
 #define MXS_AUART_DMA_RX_READY	3  /* bit 3 */
+#define MXS_AUART_RTSCTS	4  /* bit 4 */
 	unsigned long flags;
 	unsigned int ctrl;
 	enum mxs_auart_type devtype;
@@ -639,7 +640,8 @@ 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) && (s->flags & MXS_AUART_DMA_CONFIG)) {
+		if (is_imx28_auart(s) && (s->flags & MXS_AUART_DMA_CONFIG)
+				&& test_bit(MXS_AUART_RTSCTS, &s->flags)) {
 			if (!mxs_auart_dma_init(s))
 				/* enable DMA tranfer */
 				ctrl2 |= AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE
@@ -1009,6 +1011,9 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
 
 	s->flags |= MXS_AUART_DMA_CONFIG;
 
+	if (of_get_property(np, "fsl,uart-has-rtscts", NULL))
+		set_bit(MXS_AUART_RTSCTS, &s->flags);
+
 	return 0;
 }
 
-- 
1.7.4.4

[PATCH v3 1/3] serial: mxs: enable the DMA only when the RTS/CTS is valid

[Greg KH]

On Sat, Aug 03, 2013 at 10:09:14AM -0400, Huang Shijie wrote:
> From: Huang Shijie <b32955@freescale.com>
> 
> The original DMA support works only when RTS/CTS is enabled.
> (see the "e800163 serial: mxs-auart: add the DMA support for mx28")
> But after several patches, DMA support has lost this limit.
> (see the "bcc20f9 serial: mxs-auart: move to use generic DMA helper")
> 
> So an UART without the RTS/CTS lines may also enables the DMA support,
> in which case the UART may gets unpredictable results.
> 
> This patch adds an optional property for the UART DT node
> which indicates the UART has RTS and CTS lines, and it also means you
> enable the DMA support for this UART.
> 
> This patch also adds a macro MXS_AUART_RTSCTS, and uses it to check
> RTS/CTS before we enable the DMA for the UART.
> 
> Cc: stable at vger.kernel.org
> Signed-off-by: Huang Shijie <b32955@freescale.com>
> Signed-off-by: Huang Shijie <shijie8@gmail.com>
> ---
>  .../bindings/tty/serial/fsl-mxs-auart.txt          |    4 ++++
>  drivers/tty/serial/mxs-auart.c                     |    7 ++++++-
>  2 files changed, 10 insertions(+), 1 deletions(-)

I don't see how this patch follows the stable kernel guidelines, so I'll
take the marking of it off, and queue it up for 3.12.

thanks,

greg k-h

[PATCH v3 2/3] serial: mxs: remove the MXS_AUART_DMA_CONFIG

[Huang Shijie]

The MXS_AUART_DMA_CONFIG is originally used to check if the DT node
is configured with the DMA property.

But now, the MXS_AUART_DMA_CONFIG is set unconditionally in the
serial_mxs_probe_dt(), so the check in the mxs_auart_settermios() is
not necessary anymore. This patch removes this macro.

Signed-off-by: Huang Shijie <shijie8@gmail.com>
---
 drivers/tty/serial/mxs-auart.c |    5 +----
 1 files changed, 1 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index eac7b58..10e9d70 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -133,7 +133,6 @@ enum mxs_auart_type {
 struct mxs_auart_port {
 	struct uart_port port;
 
-#define MXS_AUART_DMA_CONFIG	0x1
 #define MXS_AUART_DMA_ENABLED	0x2
 #define MXS_AUART_DMA_TX_SYNC	2  /* bit 2 */
 #define MXS_AUART_DMA_RX_READY	3  /* bit 3 */
@@ -640,7 +639,7 @@ 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) && (s->flags & MXS_AUART_DMA_CONFIG)
+		if (is_imx28_auart(s)
 				&& test_bit(MXS_AUART_RTSCTS, &s->flags)) {
 			if (!mxs_auart_dma_init(s))
 				/* enable DMA tranfer */
@@ -1009,8 +1008,6 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
 	}
 	s->port.line = ret;
 
-	s->flags |= MXS_AUART_DMA_CONFIG;
-
 	if (of_get_property(np, "fsl,uart-has-rtscts", NULL))
 		set_bit(MXS_AUART_RTSCTS, &s->flags);
 
-- 
1.7.4.4

[PATCH v3 3/3] ARM: dts: imx28-evk: add the RTS/CTS property for auart0

[Huang Shijie]

From: Huang Shijie <b32955@freescale.com>

Add the RTS/CTS property for auart0 which means we enable the
DMA support for it.

Signed-off-by: Huang Shijie <b32955@freescale.com>
---
 arch/arm/boot/dts/imx28-evk.dts |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/arm/boot/dts/imx28-evk.dts b/arch/arm/boot/dts/imx28-evk.dts
index e035f46..15715d9 100644
--- a/arch/arm/boot/dts/imx28-evk.dts
+++ b/arch/arm/boot/dts/imx28-evk.dts
@@ -220,6 +220,7 @@
 			auart0: serial at 8006a000 {
 				pinctrl-names = "default";
 				pinctrl-0 = <&auart0_pins_a>;
+				fsl,uart-has-rtscts;
 				status = "okay";
 			};
 
-- 
1.7.4.4

[PATCH v3 0/3] serial: mxs-auart: add RTS/CTS check for DMA support

[Shawn Guo]

On Sat, Aug 03, 2013 at 10:09:13AM -0400, Huang Shijie wrote:
> Huang Shijie (3):
>   serial: mxs: enable the DMA only when the RTS/CTS is valid
>   serial: mxs: remove the MXS_AUART_DMA_CONFIG
>   ARM: dts: imx28-evk: add the RTS/CTS property for auart0

For the series,

Acked-by: Shawn Guo <shawn.guo@linaro.org>