Re: Fscking OMAP

[Tony Lindgren <tony@atomide.com>]

* Russell King - ARM Linux <linux@arm.linux.org.uk> [150420 10:15]:
> On Mon, Apr 20, 2015 at 09:25:16AM -0700, Tony Lindgren wrote:
> > * Russell King - ARM Linux <linux@arm.linux.org.uk> [150420 08:50]:
> > > Guys,
> > > 
> > > If you're going to introduce a dependency on some infrastructure which
> > > you absolutely require for booting, then _please_ ensure that the
> > > configuration system is updated such that pre-existing kernel
> > > configurations continue to work.
> > > 
> > > Don't leave it such that the infrastructure ends up returning -ENOSYS,
> > > which then filters down into your SoC specific code, and aborts the
> > > initialisation of critical infrastructure, leaving you with a totally
> > > silent boot failure.
> > > 
> > > In this case, it's the addition of syscon to OMAP internals,
> > > specifically in omap_control_init().
> > > 
> > > This is explicitly targetted at OMAP people, who have wasted much of
> > > my day today investigating why their platforms no longer boot in DT
> > > mode.
> > 
> > Ouch, yeah missing dependencies are a pain to debug.
> > 
> > Looks like we get MFD_SYSCON selected with omap2plus_defconfig,
> > but that's not always the case like you pointed out.
> > 
> > Does the patch below fix the issue for you?
> 
> Yes, that fixes it, thanks.

OK let's get this merged immediately and then Tero can add some more
checks to the init code like you suggested with a follow-up patch.

Regards,

Tony
 
> > 8< -----------------------
> > From: Tony Lindgren <tony@atomide.com>
> > Date: Mon, 20 Apr 2015 09:23:25 -0700
> > Subject: [PATCH] ARM: OMAP2+: Fix booting with configs that don't have MFD_SYSCON
> > 
> > With the recent changes omaps have developed a dependency to MFD_SYSCON.
> > This is used for system control module generic register area and some
> > clocks.
> > 
> > We do have it selected in omap2plus_defconfig, but targeted config
> > files may not have it selected. Let's make sure it's selected like
> > few other ARM platforms are already doing.
> > 
> > Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
> > Signed-off-by: Tony Lindgren <tony@atomide.com>
> > 
> > --- a/arch/arm/mach-omap2/Kconfig
> > +++ b/arch/arm/mach-omap2/Kconfig
> > @@ -81,6 +81,7 @@ config ARCH_OMAP2PLUS
> >  	select GENERIC_IRQ_CHIP
> >  	select MACH_OMAP_GENERIC
> >  	select MEMORY
> > +	select MFD_SYSCON
> >  	select OMAP_DM_TIMER
> >  	select OMAP_GPMC
> >  	select PINCTRL
> 
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