[PATCH] powerpc: document the "fsl, ssi-dma-channel" compatible property
From: Timur Tabi <hidden>
Date: 2008-10-10 16:52:41
The "fsl,ssi-dma-channel" compatible property is used to specify a DMA channel on the Freescale Elo DMA controller that should be used exclusively by the Freescale SSI audio controller. When a property is marked as such, the Elo DMA driver will ignore it, and so it will be available for the sound drivers. Signed-off-by: Timur Tabi <redacted> --- Documentation/powerpc/dts-bindings/fsl/dma.txt | 13 +++++++++++-- Documentation/powerpc/dts-bindings/fsl/ssi.txt | 20 ++++++++++++++------ 2 files changed, 25 insertions(+), 8 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..a2d9639 100644
--- a/Documentation/powerpc/dts-bindings/fsl/ssi.txt
+++ b/Documentation/powerpc/dts-bindings/fsl/ssi.txt@@ -24,12 +24,12 @@ 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 - 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 - capture (recording) of audio. This is typically dictated - by SOC design. See the notes below. +- 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 node for the DMA channel to use for + capture (recording) of audio. This is typically dictated + by SOC design. See the notes below. Optional properties: - codec-handle : phandle to a 'codec' node that defines an audio
@@ -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.
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1.5.5