Commit 384a290283fde63ba8dc671fca5420111cdac19a seems to break 11MPCore boot

[Will Deacon]

On Wed, Jan 30, 2013 at 05:30:06PM +0000, Nicolas Pitre wrote:
> On Wed, 30 Jan 2013, Russell King - ARM Linux wrote:
> 
> > On Wed, Jan 30, 2013 at 04:45:35PM +0000, Russell King - ARM Linux wrote:
> > > What we could do is scan interrupts 0-31 for a non-zero value.  If they're
> > > all zero, we should complain.  Otherwise, we use the first non-zero value
> > > we find and validate it for a single bit set.
> > 
> > And here's a patch to do this - I've not run this but it's just built
> > successfully here.  Anyone want to give it a go?
> > 
> > I've decided that if we do hit the mask==0 case, we should just wail
> > loudly - panic'ing will bring the kernel to a halt right there and then,
> > which may be before any console drivers have been initialized (and the
> > kernel message buffer is no longer easy to read).  Moreover, panic()ing,
> > along with the possibility of rebooting won't really fix this kind of
> > error - it's rather fatal as far as that goes.  So, I think just wailing
> > at CRIT level is fine for this condition that should not occur.
> > 
> >  arch/arm/common/gic.c |   23 +++++++++++++++++++++--
> >  1 files changed, 21 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/arm/common/gic.c b/arch/arm/common/gic.c
> > index 36ae03a..3bcef49 100644
> > --- a/arch/arm/common/gic.c
> > +++ b/arch/arm/common/gic.c
> > @@ -351,6 +351,23 @@ void __init gic_cascade_irq(unsigned int gic_nr, unsigned int irq)
> >  	irq_set_chained_handler(irq, gic_handle_cascade_irq);
> >  }
> >  
> > +static u8 gic_get_cpumask(struct gic_chip_data *gic)
> > +{
> > +	void __iomem *base = gic_data_dist_base(gic);
> > +	u8 mask, i;
> > +
> > +	for (i = mask = 0; i < 32; i++) {
> > +		mask = readl_relaxed(base + GIC_DIST_TARGET + i);
> > +		if (mask)
> > +			break;
> > +	}
> 
> That should probably be:
> 
> 	u32 mask;
> 
> 	for (i = 0; i < 32; i += 4) {
> 		mask = readl_relaxed(base + GIC_DIST_TARGET + i);
> 		mask |= (mask >> 16);
> 		mask |= (mask >> 8);
> 		if (mask)
> 			return mask;
> 	}
> 
> I know that the spec says that the GIC should accept byte sized 
> accesses, but that too is known not to work on all implementations.

Oh, for a rotation operator!

Tested-by: Will Deacon <will.deacon at arm.com>

Will