[PATCH v2 3/3] staging: nvec: add device tree support

[Marc Dietrich]

Am Donnerstag, 27. Oktober 2011, 12:17:25 schrieb Stephen Warren:
> Marc Dietrich wrote at Wednesday, October 26, 2011 1:59 PM:
> > This adds device tree support to the nvec driver. By using this method
> > it is no longer necessary to specify platform data through a board
> > file.
> 
> You should document the binding in Documentation/devicetree/bindings.

oh, I feared that ... Will go in to v3.

> > @@ -892,6 +915,17 @@ static int tegra_nvec_resume(struct platform_device *pdev)
> > 
> >  #define tegra_nvec_resume NULL
> >  #endif
> > 
> > +#if defined(CONFIG_OF)
> 
> I think you can just remove the ifdef and always include this code. Yes, it'll
> result in slightly more rodata when !CONFIG_OF, but !CONFIG_OF isn't going to
> exist or be useful for Tegra for that much longer.

ok, I will check if it causes build regressions first.

> 
> > +/* Match table for of_platform binding */
> > +static const struct of_device_id nvidia_nvec_of_match[] __devinitconst = {
> > +	{ .compatible = "nvidia,nvec", },
> 
> I'm not sure that nvidia,nvec is the right value, but need a little more
> background.
> 
> It's my understanding that how this works is a little micro-controller
> exists on the board, handles various devices like the keyboard, and sends
> data to Tegra by making I2C master transactions. Isn't it the case that
> the micro-controller (or at least the SW running on it) is board-specific,
> and the same for the I2C protocol? If so, nvidia,nvec is a little generic;
> we probably need to name it compal,paz00-ec or something like that?

The firmware (for the 8051 mc inside the keyboard controller) is likely made by 
Compal, but as Julian already said, the EC protocol definition is very likely from 
NVIDIA itself. Compal just implemented it for the master. You may refer to 
<http://nv-
tegra.nvidia.com/gitweb/?p=linux-2.6.git;a=commitdiff;h=12114faf442a8c6aac81a9702712077364db0e82>
Also this protocol is not board specific as many first generation boards/device use 
it, so "nvidia,nvec" should be correct here.

> Either way, we should probably include some kind of version number in
> the compatible property so we can support upgrades to the protocol if
> needed.

You may ask your colleagues on that topic, but it seems that the protocol is dead 
already, e.g. it wasn't implemented for the new-world kernels (>= .36) anymore.

Marc