Re: drm/msm/mdp5: undefined CONFIG_MSM_BUS_SCALING

From: Rob Clark <robdclark@gmail.com>
To: Paul Bolle <pebolle@tiscali.nl>
Cc: Greg KH <gregkh@linuxfoundation.org>,
	Valentin Rothberg <valentinrothberg@gmail.com>,
	Hai Li <hali@codeaurora.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	David Airlie <airlied@linux.ie>,
	rupran@einserver.de, stefan.hengelein@fau.de
Subject: Re: drm/msm/mdp5: undefined CONFIG_MSM_BUS_SCALING
Date: Thu, 9 Apr 2015 14:54:29 -0400	[thread overview]
Message-ID: <CAF6AEGtUVPAwxXxQ-XAFrMp=HpwVPkyVgCGQgHW6Q_6jKH8tdg@mail.gmail.com> (raw)
In-Reply-To: <1428603178.13881.20.camel@x220>

On Thu, Apr 9, 2015 at 2:12 PM, Paul Bolle <pebolle@tiscali.nl> wrote:
> On Thu, 2015-04-09 at 19:07 +0200, Greg KH wrote:
>> I really don't understand.  Why is this code in the kernel tree if it
>> can't be built?  How does anyone use this?  By taking it and copying it
>> where?  If it can't be built, and no one can update it, and of course
>> not run it, why is it here?  What good is this code doing sitting here?
>
> The Erlangen bot (courtesy of Valentin, Stefan, and Andreas) has taken
> over what I've been doing for quite some time, but doing it much more
> thoroughly. And my experience tells me that the reports they'll send in
> will trigger more discussions like this one.
>
> A lesson I learned from my daily checks for Kconfig oddities is that
> people go to great lengths defending unbuildable code. (Do a web search
> for ATHEROS_AR231X to find a discussion that dragged on for over three
> years!) Personally I stopped caring after someone insisted on having a
> file in the tree that was in no way connected to the build system: not a
> single line in any of the Makefiles pointed at it. So, as far as I'm
> concerned, if people can't point at a patch pending, somehow, somewhere,
> that would make their code buildable one might as well delete the code.
>
> I really think it's as simple as that.
>

In the example you reference, sure it is as simple as that.  But here
we are not talking about files that aren't even referenced by build
system.  We are talking about a driver which does build and run on
upstream kernel, and which has a few small #ifdef blocks to simplify
backporting to downstream kernels (which we still do need to use for
some generations and some devices)

Sure, I'd love never to have to deal with a downstream kernel.  But
really.. I didn't create the downstream mess in the arm/android
ecosystem, I'm just trying to cope with it as best as possible.. don't
hate the player, hate the game :-P

BR,
-R

>
> Paul Bolle
>