Hi Alexandre,
On Fri, 2014-09-26 at 16:13 +0200, Alexandre Belloni wrote:
> On 26/09/2014 at 13:47:03 +0200, Paul Bolle wrote :
> > On Mon, 2014-09-15 at 18:15 +0200, Alexandre Belloni wrote:
> > > From: Nicolas Ferre <nicolas.fe...@atmel.com>
> > >
> > > Signed-off-by: Nicolas Ferre <nicolas.fe...@atmel.com>
> >
> > This landed in next-20140926, as commit 2dc850b62e5b ("ARM: at91:
> > introduce basic SAMA5D4 support").
> >
> > > diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
> > > index b11ad54f8d17..7b44db208f10 100644
> > > --- a/arch/arm/Kconfig.debug
> > > +++ b/arch/arm/Kconfig.debug
> > > @@ -101,6 +101,10 @@ choice
> > > bool "Kernel low-level debugging on 9263 and 9g45"
> > > depends on HAVE_AT91_DBGU1
> > >
> > > + config AT91_DEBUG_LL_DBGU2
> > > + bool "Kernel low-level debugging on sama5d4"
> > > + depends on HAVE_AT91_DBGU2
> > > +
> >
> > Why is this Kconfig symbol needed? Nothing in next-20140926 uses it. Are
> > future users perhaps queued somewhere (say, in commits that didn't
> > survive today's rather lively linux-next merges)?
>
> There is no user because it conflicts with the previous one that is
> selected by default by the sama5_defconfig. This is for early print and
> it means that you can get earlyprintk either for sama5d3 or sama5d4.
>
> My guess is that it will never be included in any defconfig.
I missed that this is inside a "choice" (which complicates matters quite
a bit)!
There are a number of cases where one of the configs inside the choice
only serve to _not_ set anything. In those cases the Kconfig symbol is
used nowhere else. I'll have to think about this particular symbol a bit
more to see if it actually makes sense to not use it anywhere else.
Thinking about the "Kernel low-level debugging port" choice is
complicated by the fact that it holds about a gazillion "config"
entries, many of which only show up only if some dependency is met. So
it might take me some time to say anything sensible about it, if I ever
manage to do that at all...
Thanks,
Paul Bolle
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