[Gta04-owner] Android gadget driver

Dr. H. Nikolaus Schaller hns at goldelico.com
Sat Aug 3 18:34:30 CEST 2013


Am 03.08.2013 um 13:28 schrieb Belisko Marek:

> Hi All,
>> 
>> Oops - that is sad.
> I've contacted John Stultz (responsible for mainlinig android at

Great!

> linaro) with question about gadget driver and he replied:
> 
> So for now, there isn't a replacement for the Android Gadget driver.
> The ccg was sort of a half step that was quickly abandoned. The
> eventual replacement should be the ConfigFS Gadget driver. Some
> portions of which have landed upstream, but I've not yet been able to
> research if its sufficient to replace the Android Gadget driver.
> 
> If you want to look into it, you can find the commit here:
> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=88af8bbe4ef781031ad3370847553f3b42ba0076
> 
> I'm hoping to discuss this further at the Linux Plumbers Conference
> Android Micro-conf.
> 
> As for Linaro Android Kernels, those should include the Android Gadget
> driver patches.
> 
> Hope this helps explain things.

I have found out a little more. The original Android Gadget driver was
contributed at 16th May 2012 to 3.5-rc2 (and some variables were
renamed to "ccg"):

http://lxr.free-electrons.com/source/drivers/staging/ccg/ccg.c?v=3.5
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=332bb43f7c4baea2a0dce7ae2c078c55e14d37b5

As far as I can see, in Linux 3.6 there were only minor changes.

In 3.7 they started to rework things up to 3.9. But work stalled at
22th Oct. And in 3.10 it was removed completely as said above...

I have no problem with using the /sys interface and as long as Replicant
wants to control it through /sys, we need to have a driver that supports /sys...

So the best approach appears to me to merge the ccg from 3.5 or 3.6 (before
it was touched to add functionfs support) into our 3.11. It should suffice to
cherry-pick 332bb43f7c4baea2a0dce7ae2c078c55e14d37b5 and fix
issues.

This will of course never go upstream, but I hope it is a solution for
Replicant's need of a good kernel with adb support.

BR,
Nikolaus



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