Message-ID: <CAPweEDwFHY_AbBxjspm7BvfdFHsxL5H594cFN4ZVC6QFpu4QGA@mail.gmail.com>
Date:	Sat, 8 Jun 2013 00:07:28 +0100
From:	"luke.leighton" <luke.leighton@...il.com>
To:	Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Tomasz Figa <tomasz.figa@...il.com>,
	linux-arm-kernel@...ts.infradead.org,
	devicetree-discuss <devicetree-discuss@...abs.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	debian-arm@...ts.debian.org,
	"jonsmirl@...il.com" <jonsmirl@...il.com>,
	Linux on small ARM machines 
	<arm-netbook@...ts.phcomp.co.uk>, debian-kernel@...ts.debian.org
Subject: Re: [Arm-netbook] getting allwinner SoC support upstream (was Re:
 Uploading linux (3.9.4-1))

On Fri, Jun 7, 2013 at 11:08 PM, Maxime Ripard
<maxime.ripard@...e-electrons.com> wrote:
> On Fri, Jun 07, 2013 at 07:26:49PM +0100, luke.leighton wrote:
>>  maxime: we need to talk :)
>>
>>  please tell me in 4 or 5 sentences what you've managed to do so far,
>> expanding a little on what thomas says below, more specifically what
>> it achieves and/or allows rather than technically what it does
>> (suitable for managers and directors in other words), and what plans
>> you'd like to see happen.
>
> You mean something like http://linux-sunxi.org/Linux_mainlining_effort ?

 ahh, fantastic.  with references too.  magic.  exactly what i need.
thank you.  listed now at
http://hands.com/~lkcl/allwinner_linux_proposal.txt

> You should really do a bit of research before starting a thread like
> this one.

 then that gives you some idea of how busy i've been and still am, to
not be aware even of things like this, to have kicked a project off
some 18-24 months ago and not be able to keep up with one of the many
branches and initiatives that it's spawned.

 when i said i've been caught off-guard by this opportunity i meant
exactly what i said.

> This webpage has been around for like 9 monthes now on the wiki
> of a community you pretend to represent

 i pretend no such thing and apologise for giving any impression of such.

> (even though I fail to get how
> you can pretend such thing, but that's another topic).

 i have a different focus: a meta-project of sorts, where allwinner
happened to be the first.  look up rhombus-tech and EOMA68 and it'll
become a bit clearer.

>> > is the maintainer of the mainline Allwinner sunxi
>> > effort. It already supports a number of boards, has a pinctrl driver, a
>> > GPIO driver, serial port is working, network is working, I2C is
>> > working.
>> >
>> > All in mainline, completely Device Tree based.
>>
>>  great.  which version did it first hit, i.e. what will the first
>> signs of this be when allwinner begin doing "git pulls"?
>
> 3.8, as shown in the wiki page

 got that.

>>  and which boards.  bear in mind that one of those "boards" should
>> really be "the total range of products available across hundreds of
>> chinese tablet clone manufacturers".
>>
>>  specific question: is one of the "boards" the one that tom cubie
>> submitted, which covers virtually every android tablet product
>> manufactured in the millions by chinese tablet clone manufacturers?
>
> Again, wiki.

 yep, am there now.

>> > So isn't this entire discussion completely moot?
>>
>>  no because it's totally in isolation from allwinner.  i need to give
>> them a heads-up, and get them involved, giving them specific
>> incentives [which nobody's yet given!!] for following a particular
>> path [or paths] yet to be recommended.
>>
>> > The mainline support
>> > for sunxi has already started since 6 months or so, and has been Device
>> > Tree based from day one.
>>
>> to clarify: the *community-driven* mainline support for sunxi.  ok -
>> which chips?  sun3i (ARM9), sun4i (Cortex A8), sun5i, sun6i and sun7i
>> (Dual-Core Cortex A7)?  which ones are in?
>
> A10, A13 for the moment. I just received hardware with A10s, A20 and A31
> that I need to work on, but support should come quite soon.

 superb.  question: what help or other resources could you do with?
what additional information?


> I already
> have some patches pending to be tested on an A31 board, but didn't have
> as much time as I wanted lately to actually set a proper environment to
> test them.

 ok - good to know.  btw when you get to it please note a bug found in
the "vanilla" [allwinner-released] A20 3.3 tree where they reduced a
128 byte buffer to 78 bytes for spurious reasons; the critical fix is
at line 989, of the following patch:

 http://git.rhombus-tech.net/?p=linux.git;a=commitdiff;h=refs/heads/lkcl-3.3-a20;hp=6c5753e5dc1fafff288d522c94b40a7dd2a81adc

 i found this by running a diff -u of sun4i_usb from the 3.4 sunxi
community tree against the sun7i_usb tree from the allwinner 3.3
release.  amongst the desperate attempts to disable DMA (probably due
to stack corruption of the above bug) and various renaming attempts of
*SUN4I* to *SUN7I*, that one stuck out like a sore thumb.  the other
bits - which may or may not be relevant - are the spinlock protection
and the call to sw_udc_enable which is present in the sun4i_usb 3.4
code but not the A20 3.3 code.

mileage may vary, and the buffer overrun only happens if you enable
the OTG interface as "dual" (auto-detect) because that's enough
features in the bitfield to cause there to be enough strcpy's... oops
:)

l.
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