Re: [Ksummit-discuss] [CORE TOPIC] Mainline kernel on a cellphone

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Wednesday 29 July 2015 09:45:22 Krzysztof Kozlowski wrote:
> On 29.07.2015 07:09, Tim Bird wrote:
> > On 07/23/2015 08:40 AM, Mark Brown wrote:
> >> On Thu, Jul 23, 2015 at 08:42:51AM -0400, Steven Rostedt wrote:
> >>> Although is this something to be a core topic or a tech topic? Does
> >>> this affect all subsystems, or just a set of drivers? Note, a core
> >>> topic wont get as much time for discussion as a tech topic would.
> >> 
> >> It's basically all subsystems that get impacted, at the minute I'd say
> >> it's more a plan of action and process discussion than a technical one
> >> though in the context of KS planning that's quite probably the same
> >> thing.
> >> 
> >>> Also, what is expected to be solved at KS?
> >> 
> >> Tim Bird (Cced) has been running some sessions at other conferences
> >> scoping the problem and discussing ways to move forward on this, another
> >> similar session might be useful.
> > 
> > As Mark says, I've been working on almost exactly this topic for several
> > months now.  Last year I conducted a survey investigating obstacles
> > that developers (mostly corporate product developers) have in mainlining.
> > There are lots of non-technical issues that are worth working on (version
> > gap, corporate incentives, training, etc.), but which are outside
> > the scope of the kernel summit.
> > 
> > There are also some technical areas where I think coordinated
> > effort might be useful, to identify deficiencies and collaborate on
> > progress.  These might be worth discussing at the summit.
> > 
> > In March of this year, I analysed code from several shipping phones
> > (representing a number of different SoCs, including both ARM and
> > Intel-architecture CPUs), and found that most products have between
> > 1.2 and 3 million lines of code out-of-tree.  We are still in progress of
> > finding patterns of out-of-treeness, to inform decisions about technical
> > projects going forward.
> > 
> > There is now a wiki page at:
> > See http://elinux.org/Kernel_areas_of_focus_for_mainlining
> > In particular it has a table showing certain areas that tend to have
> > a lot of out-of-tree code (e.g. most phones have between 80K to
> > 100K of lines of wireless driver support out-of-mainline)
> 
> Did anyone see successful attempts of mainlining such vendor code? I
> mean mainlining by individuals, not by vendor company itself.
> 
> It is a difficult task, especially without datasheets but it's possible.
> At least for some drivers.
> 
> If there were such efforts, I would be curious what obstacles he/she
> encountered (except a common one - missing datasheet/specs) and how he
> can be helped?

Given the dubious (to remain polite) quality of most out-of-tree vendor code, 
mainlining such drivers requires kernel guru skills and that's a very scarce 
resource. One big issue in my opinion is that people who have the necessary 
skills just lack free time. We would need to find budget to make that happen.

-- 
Regards,

Laurent Pinchart