From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
Subject: Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for
 NVIDIA ADMA
Date: Tue, 6 Oct 2015 17:04:09 -0600
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On 10/05/2015 06:10 AM, Jon Hunter wrote:
> Add device-tree binding documentation for the Tegra210 Audio DMA
> controller.

> diff --git a/Documentation/devicetree/bindings/dma/tegra210-adma.txt b/Documentation/devicetree/bindings/dma/tegra210-adma.txt

> +- #dma-cells : Must be <2>. The first cell denotes the transmit or
> +  receive request number and should be between 1 and the maximum number
> +  of requests supported (see properties "dma-rx-requests" and
> +  "dma-tx-requests"). This value corresponds to the RX/TX_REQUEST_SELECT
> +  fields in the ADMA_CHn_CTRL register. The second cell denotes whether
> +  the channel is a receive or transmit channel and must be either 2 for
> +  a receive channel and 4 for a transmit channel. These values correspond
> +  to the TRANSFER_DIRECTION field of the ADMA_CHn_CTRL register.

Is it typical to encode the direction into the dma cells? I would have 
thought the client would provide that information at run-time when 
requesting a DMA channel.