powerpc: document the "fsl,ssi-dma-channel" compatible property

[linux-2.6-omap-h63xx.git] / Documentation / powerpc / dts-bindings / fsl / dma.txt

diff --git a/Documentation/powerpc/dts-bindings/fsl/dma.txt b/Documentation/powerpc/dts-bindings/fsl/dma.txt
index 86826df00e64ea66085c387d7fd68db46211963c..cc453110fc4651bcbc135e2dfc163e45776eb574 100644 (file)
--- 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.