Question: DTS and redundant board IDs

Question: DTS and redundant board IDs

[David Lanzendörfer]

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Hello
As you certainly already have heard some manufacturers are using the same
board ID for multiple devices.
For instance, the NotionInk Adam registers as harmony board,
while it's pinmuxing differs in fact a lot.
My question:
How could this be handled by DTS?
ATM I'm compiling the kernel with only the adam board enabled, but I'd like to
integrate the muxing information into DTS in order to get it running on top
of upstream.

Any suggestions?

Thx a lot in advance

-lev

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Re: Question: DTS and redundant board IDs

[Stephen Warren]

On 05/03/2012 08:50 AM, David Lanzendörfer wrote:
> Hello
> As you certainly already have heard some manufacturers are using the same
> board ID for multiple devices.
> For instance, the NotionInk Adam registers as harmony board,
> while it's pinmuxing differs in fact a lot.
> My question:
> How could this be handled by DTS?

The machine ID isn't relevant with device tree; just supply the correct
content in device tree and it'll work out fine.

Re: Question: DTS and redundant board IDs

[Stephen Warren]

On 05/04/2012 02:47 AM, David Lanzendörfer wrote:
> Hi
> Thanks a lot for your answer!
> 
>> The machine ID isn't relevant with device tree; just supply the correct
>> content in device tree and it'll work out fine.
>
> How do I tell the kernel on which device within the tree it's running on?

The kernel shouldn't really care; the DT support is designed to mostly
only directly know about Tegra20 vs. Tegra30.

> Where can I get the correct string from for adding into pinmux_configs?

You'll have to create it yourself by translating the content of the
board pinmux file in whatever kernel the board currently uses.

I do have a very rough Python script that mostly converts the format,
but it's got a lot of warts. I can email that to you directly if you
want. You will need to manually patch up some of the results though.

> In upstream there are strings like "compulab,trimslice" or "nvidia,harmony".
> Where can I extract the correct string for adam?

You will have to create it yourself based on the vendor and board name.
I think what you want is something like:

compatible = "notionink,adam", "nvidia,tegra20";

> Sry, but until now, I've just used the hw id and it worked... :-/
> 
> Is there a documentation and I'm just unable to find it?

In the kernel source, Documentation/devicetree/bindings describes the
format of all the device tree nodes. See e.g.
pinctrl/nvidia,tegra20-pinmux.txt. Also, be sure to become familiar with
how the other Tegra device trees are constructed; see
arch/arm/board/dts/tegra*.