Raspberry Pi Upstreaming

Stephen Warren swarren at wwwdotorg.org
Thu Oct 16 19:47:38 PDT 2014

On 10/16/2014 06:02 AM, Lee Jones wrote:
> So, I'm interested in helping out with the Raspberry Pi Kernel
> Upstreaming effort.  I found [1], but there isn't any information on
> the critical stuff; mainlining status, who's working on what,
> outstanding tasks, etc.

The primary missing features are anything that relies on the VC
(VideoCore) firmware, i.e.:

* Clocks
* Display (except via simplefb)
* Graphics
* VC firmware mailbox/... driver, as support for the above.

Things like SD card (faster transfer modes or timing tweakings) or USB
might need some tweaking.

I don't know of anyone working on those (except DWC2 USB which Synopsys
is now actively contributing to). I had hoped that by getting something
running in the mainline kernel, the RPi Foundation would come along and
finish the job. However, I that hasn't happened unfortunately.

I've personally deliberately avoided coding anything up that relies on
the firmware interface. I'm not sure if the interface to firmware is
guaranteed to be an ABI. The documented messages don't tell the whole
story; someone with more knowledge of the firmware/chip would be needed
to correctly model the parent/child links in the clock tree for example.
I had hoped that someone would complete the VC reverse-engineering
effort (or make use of the headers published along with the graphics
source code) and write either open firmware or Linux-hosted drivers.

> Is there a Wiki with more information on this?
> How about an IRC channel that we can talk on informally?

I am on #armlinux, although mostly during work time when I shouldn't be
discussing RPi stuff.

To be honest, I haven't been using my Pi much recently. If you have the
motivation to take over as Pi maintainer, or simply start sorting out
the best approach to VC firmware and pushing on the layers above that,
I'd be OK with that.

> [1] http://elinux.org/RPI_Upstreaming

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