[PATCH] powerpc: fix conflict with Elo DMA driver in MPC8610 device tree

[Timur Tabi]

The Freescale Elo DMA driver binds to all DMA channels in the device tree that
are compatible with "fsl,eloplus-dma-channel".  This conflicts with the sound
drivers for the MPC8610.  To avoid the conflict, change the compatible property
for the DMA channels needed by the sound drivers to "fsl,ssi-dma-channel".
This works because the sound drivers don't actually check the compatible
property when it grabs DMA channels.

Also update dma.txt and ssi.txt with this information.

Signed-off-by: Timur Tabi <timur at freescale.com>
---
 Documentation/powerpc/dts-bindings/fsl/dma.txt |   13 +++++++++++--
 Documentation/powerpc/dts-bindings/fsl/ssi.txt |   12 ++++++++++--
 arch/powerpc/boot/dts/mpc8610_hpcd.dts         |    4 ++--
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/Documentation/powerpc/dts-bindings/fsl/dma.txt b/Documentation/powerpc/dts-bindings/fsl/dma.txt
index 86826df..cc45311 100644
--- a/Documentation/powerpc/dts-bindings/fsl/dma.txt
+++ b/Documentation/powerpc/dts-bindings/fsl/dma.txt
@@ -20,7 +20,7 @@ Required properties:
         - compatible        : compatible list, contains 2 entries, first is
 			 "fsl,CHIP-dma-channel", where CHIP is the processor
 			 (mpc8349, mpc8350, etc.) and the second is
-			 "fsl,elo-dma-channel"
+			 "fsl,elo-dma-channel". However, see note below.
         - reg               : <registers mapping for channel>
         - cell-index        : dma channel index starts at 0.
 
@@ -82,7 +82,7 @@ Required properties:
         - compatible        : compatible list, contains 2 entries, first is
 			 "fsl,CHIP-dma-channel", where CHIP is the processor
 			 (mpc8540, mpc8560, etc.) and the second is
-			 "fsl,eloplus-dma-channel"
+			 "fsl,eloplus-dma-channel". However, see note below.
         - cell-index        : dma channel index starts at 0.
         - reg               : <registers mapping for channel>
         - interrupts        : <interrupt mapping for DMA channel IRQ>
@@ -125,3 +125,12 @@ Example:
 			interrupts = <17 2>;
 		};
 	};
+
+Note on DMA channel compatible properties: The compatible property must say
+"fsl,elo-dma-channel" or "fsl,eloplus-dma-channel" to be used by the Elo DMA
+driver (fsldma).  Any DMA channel used by fsldma cannot be used by another
+DMA driver, such as the SSI sound drivers for the MPC8610.  Therefore, any DMA
+channel that should be used for another driver should not use
+"fsl,elo-dma-channel" or "fsl,eloplus-dma-channel".  For the SSI drivers, for
+example, the compatible property should be "fsl,ssi-dma-channel".  See ssi.txt
+for more information.
diff --git a/Documentation/powerpc/dts-bindings/fsl/ssi.txt b/Documentation/powerpc/dts-bindings/fsl/ssi.txt
index 5d98413..f11ec34 100644
--- a/Documentation/powerpc/dts-bindings/fsl/ssi.txt
+++ b/Documentation/powerpc/dts-bindings/fsl/ssi.txt
@@ -24,10 +24,10 @@ Required properties:
 		    "rj-master" - r.j., SSI is clock master
 		    "ac97-slave" - AC97 mode, SSI is clock slave
 		    "ac97-master" - AC97 mode, SSI is clock master
-- fsl,playback-dma: phandle to a DMA node for the DMA channel to use for
+- fsl,playback-dma: phandle to a node for the DMA channel to use for
 		    playback of audio.  This is typically dictated by SOC
 		    design.  See the notes below.
-- fsl,capture-dma:  phandle to a DMA node for the DMA channel to use for
+- fsl,capture-dma:  phandle to a node for the DMA channel to use for
 		    capture (recording) of audio.  This is typically dictated
 		    by SOC design.  See the notes below.
 
@@ -51,3 +51,11 @@ playback and DMA channel 1 for capture.  SSI2 must use DMA channel 2 for
 playback and DMA channel 3 for capture.  The developer can choose which
 DMA controller to use, but the channels themselves are hard-wired.  The
 purpose of these two properties is to represent this hardware design.
+
+The device tree nodes for the DMA channels that are referenced by
+"fsl,playback-dma" and "fsl,capture-dma" must be marked as compatible with
+"fsl,ssi-dma-channel".  The SOC-specific compatible string (e.g.
+"fsl,mpc8610-dma-channel") can remain.  If these nodes are left as
+"fsl,elo-dma-channel" or "fsl,eloplus-dma-channel", then the generic Elo DMA
+drivers (fsldma) will attempt to use them, and it will conflict with the
+sound drivers.
diff --git a/arch/powerpc/boot/dts/mpc8610_hpcd.dts b/arch/powerpc/boot/dts/mpc8610_hpcd.dts
index 855f70c..f724d72 100644
--- a/arch/powerpc/boot/dts/mpc8610_hpcd.dts
+++ b/arch/powerpc/boot/dts/mpc8610_hpcd.dts
@@ -237,7 +237,7 @@
 
 			dma00: dma-channel at 0 {
 				compatible = "fsl,mpc8610-dma-channel",
-					"fsl,eloplus-dma-channel";
+					"fsl,ssi-dma-channel";
 				cell-index = <0>;
 				reg = <0x0 0x80>;
 				interrupt-parent = <&mpic>;
@@ -245,7 +245,7 @@
 			};
 			dma01: dma-channel at 1 {
 				compatible = "fsl,mpc8610-dma-channel",
-					"fsl,eloplus-dma-channel";
+					"fsl,ssi-dma-channel";
 				cell-index = <1>;
 				reg = <0x80 0x80>;
 				interrupt-parent = <&mpic>;
-- 
1.5.5