linux-kernel - Re: [GIT PULL] interconnect changes for 5.5

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Message-ID: <20191110101647.GA1441986@kroah.com>
Date:   Sun, 10 Nov 2019 11:16:47 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Georgi Djakov <georgi.djakov@...aro.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Subject: Re: [GIT PULL] interconnect changes for 5.5

On Sat, Nov 09, 2019 at 12:27:29PM -0800, Bjorn Andersson wrote:
> On Sat, Nov 9, 2019 at 12:48 AM Greg Kroah-Hartman
> <gregkh@...uxfoundation.org> wrote:
> >
> > On Fri, Nov 08, 2019 at 05:36:46PM -0800, Bjorn Andersson wrote:
> > > On Fri, Nov 8, 2019 at 2:39 AM Greg Kroah-Hartman
> > > <gregkh@...uxfoundation.org> wrote:
> > > >
> > > > On Thu, Nov 07, 2019 at 05:42:13PM +0200, Georgi Djakov wrote:
> > > > > Hi Greg,
> > > > >
> > > > > On 11/7/19 16:21, Greg Kroah-Hartman wrote:
> > > > > > On Thu, Nov 07, 2019 at 02:46:53PM +0200, Georgi Djakov wrote:
> > > > > >> Hi Greg,
> > > > > >>
> > > > > >> This is a pull request with interconnect patches for the 5.5 merge window.
> > > > > >> All patches have been for a while in linux-next without reported issues. The
> > > > > >> details are in the signed tag. Please consider pulling into char-misc-next.
> > > > > >
> > > > > > I don't know about
> > > > > > 0003-interconnect-Disallow-interconnect-core-to-be-built-.patch here.
> > > > > > Shouldn't you just fix up the dependancies of subsystems that rely on
> > > > > > this?  We are moving more and more to kernels that "just work" with
> > > > > > everything as modules, even on arm64 systems.  So forbiding the
> > > > > > interconnect code from being able to be built as a module does not feel
> > > > > > good to me at all.
> > > > >
> > > > > Thank you for commenting on this! The initial idea was to keep everything as
> > > > > modular as possible. The reasons behind this change is that other core
> > > > > frameworks like cpufreq (and possibly others) want to call the interconnect
> > > > > APIs. Some of these frameworks are built-in only and it would be easier to
> > > > > handle dependencies if interconnect core built-in too. Now each user that
> > > > > can be built-in has to specify in Kconfig that it depends on INTERCONNECT ||
> > > > > !INTERCONNECT.
> > > >
> > > > That's fine, when those subsystems start to use those apis, that
> > > > dependency needs to be added.  Nothing new here, and you forcing it to
> > > > either be "on or off" isn't going to change that.  Let's do it correctly
> > > > please.
> > > >
> > >
> > > Please no!
> > >
> > > Making our frameworks tristate means that we can no longer rely on
> > > include file stubs (as framework=m, client=y will fail), so every
> > > single client must add the "depends on framework || framework=n" - in
> > > contrast to nothing the framework itself is bool.
> >
> > What's wrong with a single "depends on framework"?  If your code relies
> > on this framework, you should depend on it, right?
> 
> As your question shows, everyone gets this wrong and the build breaks
> all the time (it's not "depends on framework", it's "depends on
> framework || framework=n" - and everyone you'll talk to will be
> puzzled as to why this is).

Ah, now I get it.  Yeah, that sucks.  We need a "shortcut" in Kconfig to
express that type of dependancy.

thanks,

greg k-h