Re: [PATCH 0/2] ARM: dts: Add DT bindings for OMAP SDMA

Hi Jon,

On 02/06/2013 10:03 PM, Jon Hunter wrote:

Adds device-tree bindings from SDMA on OMAP2+ devices. DMA client
bindings are also added for devices that have SPI and MMC bindings
populated. Client binding data is based upon existing HWMOD data for
OMAP and has been checked against OMAP documentation.

Testing includes ...
1. Boot tested on OMAP3430 Beagle board, OMAP4430 Panda board and
   OMAP4460 Panda board with and without device-tree present.
2. Testing of MMC1 with SD card on OMAP3430 Beagle board, OMAP4430
   Panda board and OMAP4460 Panda board with and without device-tree
   present.

I looked briefly around in the mentioned code and I wonder how this is going
to work with audio (ASoC).
When we boot with DT it looks like we are _not_ creating the DMA resources for
the device as it is done for the IRQ and IO/MEM. So this means that we can not
use get_resource*() for DMA anymore when we move to DT.
This might be OK for (OMAP)mmc, (OMAP)spi, etc. But in audio we have a common
library used by all platforms to deal with the dmaengine.
I don't think we can switch to use dma_request_slave_channel_compat() in
soc-dmaengine-pcm.c. We need to pass the dma channel number to the lib from
the ASoC platform drivers. Or we need to synchronize the order of the dmas and
the dma-names around all SOCs in existence?

Has anyone thought about this?

CC-ing Mark Brown and Lars-Peter Clausen they might already know the answer to
this.

Testing branch available here [1].

Series is based upon v3.8-rc6 on top of the following ...
- Vinod's topic/dmaengine_dt branch [2]
- Matt Porter's series "DMA Engine support for AM33XX" [3]
- Matt Porter's series "omap_hsmmc DT DMA Client support" [4]
- Sourav Poddar's series "add omap mcspi device tree data" [5]

[1] https://github.com/jonhunter/linux/commits/dev-dt-dma
[2] http://git.infradead.org/users/vkoul/slave-dma.git/shortlog/refs/heads/topic/dmaengine_dt
[3] http://permalink.gmane.org/gmane.linux.kernel.spi.devel/12508
[4] http://permalink.gmane.org/gmane.linux.ports.arm.omap/93165
[5] http://permalink.gmane.org/gmane.linux.kernel/1435002

Jon Hunter (2):
  ARM: dts: OMAP2+: Add SDMA controller bindings and nodes
  dmaengine: OMAP: Register SDMA controller with Device Tree DMA driver

 .../devicetree/bindings/dma/omap-sdma.txt          |   44 ++++++++++++++++++++
 arch/arm/boot/dts/omap2.dtsi                       |   12 ++++++
 arch/arm/boot/dts/omap3.dtsi                       |   40 ++++++++++++++++++
 arch/arm/boot/dts/omap4.dtsi                       |   41 ++++++++++++++++++
 arch/arm/boot/dts/omap5.dtsi                       |   41 ++++++++++++++++++
 drivers/dma/omap-dma.c                             |   31 +++++++++++++-
 6 files changed, 208 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/devicetree/bindings/dma/omap-sdma.txt

-- 
Péter
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