rk2918 support

[Steven Newbury]

On Sat, 2014-10-04 at 10:49 +0900, Naoki FUKAUMI wrote:
> Hi
> 
> On Sat, Oct 4, 2014 at 6:37 AM, Heiko Stübner <heiko at sntech.de> 
> wrote:
> > > How
> > > much work would it be to get it forward ported along the lines 
> > > of the
> > > other Rockchip SoC code?
> > 
> > After getting some output on the console, you would work your way 
> > up.
> > Clocksource/clockeven is still the dw_apb_timer (already 
> > supported). The
> > hardest part will probably be getting a real clock-tree from the 
> > clock.c in
> > the second git repo you linked.
> 
> that git repo is not "updated" not "generic" not "rockchip" repo. and
> all history(authors and patches) were erased, it's impossible to 
> reuse
> it.
> 
> then, this is "updated" "rockchip" repo
>  https://github.com/linux-rockchip/kernel_rockchip (rockchip-3.0-
> stable branch)
> 
> it's came from Rockchip's tablet SDK. it's not same as kernel in R-
> BOX
> SDK, but I think it can be called as "generic"(no unknown/random
> change).
> 
I decided I would try to create a baseline working kernel from the 
above "generic" tree to start with from before attempting to covert it 
to device-tree and update/port the drivers for mainline.

I spent quite a few hours yesterday trying to pull in the vendor 
changes (from the Archos specific machine sources) for my tablet, and 
getting the thing to build.  Unfortunately the code is a bit of a 
mess, and the rk2918 (rk29) gpio code doesn't want to build yet.  I 
don't think the rk29 code has had a lot of love in the "generic" tree, 
although it at least exists!

The vendor changes mostly consisted of the usual machine specific 
changes, but quite a few drivers were just copied with hard-coded 
hacks to make them work with this board.

I'm getting to the point where I'm wondering whether it would be less 
work to just start using the information from the vendor tree to fill 
out support for my machine in mainline and then bring the drivers 
across and cross my fingers...

Is there anything Cortex-A9 specific in the new Rockchip support?  
Should a mach-rockchip kernel boot on my rk2918 (Cortex-A8), or should 
I be looking at making it a separate "mach-rk29" as the original port 
did?

My plan right now, is to update the gpio code in the original rk29 
port to bring it in line with the rk30 port, and clean it up.  Get rid 
of the duplicated drivers and make the machine specific changes 
"#ifdef" or runtime configurable within the original versions.  
Hopefully, I'll then be able to build a kernel with that tree make 
sure everything works.  Once that's done I'm going to start converting 
it to device-tree/pinctrl against linus' tree, unless there's a more 
suitable target?

I'm thinking I'll only going to put in the pieces to make it work with 
my board, since I can't test anything else, unless somebody with the 
hw wants to volunteer to test it?  I'm not sure whether I should port 
the rk29sdk as the machine with my board as a variant, as the original 
port did, or just create a port for my machine, maybe that will become 
obvious as I dig into device-tree?

Any advice or comments with the above?
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