On Tue, Apr 30, 2013 at 09:11:19AM +0200, Guennadi Liakhovetski wrote:
> Previously an issue has been discussed, arising on sh-/r-mobile ARM-based
> systems. There we typically have multiple DMA controller instances with
> exactly equal or very similar capabilities. Each of them can serve the same
> slaves, using the same slave identifiers (request line IDs). With the
> present DMA DT implementation _each_ such DMA slave would have to reference
> _each_ of those DMA controllers in its DMA bindings, e.g.
But why... if that is the case then we havent define DT-bindings clearly enough
And we havent merged that yet, so why not fix that in first set itself
--
~Vinod
>
> mmc0: mmc@10000000 {
> ...
> dmas = <&dma0 0x10
> &dma1 0x10
> &dma2 0x10
> &dma3 0x10
> &dma0 0x11
> &dma1 0x11
> &dma2 0x11
> &dma3 0x11>;
> dma-names = "tx", "tx", "tx", "tx",
> "rx", "rx", "rx", "rx";
> };
>
> Which certainly isn't pretty. To avoid such redundancy it has been proposed
> to implement a DMA multiplexer DT node. That way slaves would just
> reference the multiplexer and one of DMA controller instances in it would
> be picked up automatically to provide DMA channels to slaves. Patches 1-3
> in this series propose such an implementation. Patch 4 is just a minor
> clean up, can be applied independently.
>
> Cc: Guennadi Liakhovetski <g.liakhovetski+rene...@gmail.com>
>
> Guennadi Liakhovetski (4):
> OF: add a new phandle parsing function for grouped nodes
> dmaengine: add support for DMA multiplexer DT nodes
> ARM: shmobile: move r8a7740 DMA controller DT node under a "dma-mux"
> node
> OF: modify function stubs to match proper function declarations.
>
> Documentation/devicetree/bindings/dma/dma.txt | 44
> ++++++++++++++++++++
> .../boot/dts/r8a7740-armadillo800eva-reference.dts | 12 +++---
> arch/arm/boot/dts/r8a7740.dtsi | 43 +++++++++++--------
> drivers/dma/of-dma.c | 39 +++++++++++++----
> drivers/of/base.c | 28 +++++++++++-
> include/linux/of.h | 20 ++++++++-
> 6 files changed, 147 insertions(+), 39 deletions(-)
>
> --
> 1.7.2.5
>
> Thanks
> Guennadi
> ---
> Guennadi Liakhovetski, Ph.D.
> Freelance Open-Source Software Developer
> http://www.open-technology.de/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
