Re: DT DMA channel binding for Tegra I2S

[Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Mark,

On 11/25/2011 10:09 AM, Mark Brown wrote:
> On Fri, Nov 25, 2011 at 09:55:23AM -0600, Rob Herring wrote:
> 
>> Although, I think you are possibly missing some other properties for
>> i2s mode like word size and master/slave mode. I think the ideal case
>> is that a single ASoC platform driver for DT could handle multiple
>> SoCs.
> 
> No.  You're not going to be able to get a single binding which handles
> the setup for all systems based off a given SoC let alone multiple SoCs.
> It is possible to come up with some subsets which work over multiple
> boards but that's going to be outside the binding for the I2S controller
> and in a board audio hardware binding for the subset.

I never said a single binding. Part of device tree is describing how
devices are connected together which is a large part of the audio
configuration. Whether there's one common driver or not doesn't really
matter. The important part right now is to define the bindings and do so
in a common way where possible.

My original point really was that when defining a binding, it should be
as complete as possible rather than done incrementally over time. You
are describing the h/w, and that's not changing. For an i2s block, only
having a dma channel is definitely not complete.

> This has been discussed repeatedly, we really need to work out how to
> educate device tree people about this stuff, it gets *very* repetitive
> having the discussion over and over again.

As you might guess, audio is not an area I have been spending time on
recently. Perhaps seeing a complete binding with all the pieces (codec,
i2s, misc gpio's, etc.) would help educate us.

Rob