Subject: [PATCH v2 1/2] arm64: dts: zx: Fix gic GICR property

From: [email-masked] (Shawn Guo)
Date: Sat, 3 Dec 2016 17:22:55 +0800

On Fri, Dec 02, 2016 at 05:02:28PM +0000, Marc Zyngier wrote:
> Just noticed this.
> 
> On 13/10/16 13:31, Jun Nie wrote:
> > GICR for multiple CPU can be described with start address and stride,
> > or with multiple address. Current multiple address and stride are
> > both used. Fix it.
> > 
> > vmalloc patch 727a7f5a9 triggered this bug:
> > [    0.097146] Unable to handle kernel paging request at virtual address ffff000008060008
> > [    0.097150] pgd = ffff000008602000
> > [    0.097160] [ffff000008060008] *pgd=000000007fffe003, *pud=000000007fffd003, *pmd=000000007fffc003, *pte=0000000000000000
> > [    0.097165] Internal error: Oops: 96000007 [#1] PREEMPT SMP
> > [    0.097170] Modules linked in:
> > [    0.097177] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0+ #1474
> > [    0.097179] Hardware name: ZTE zx296718 evaluation board (DT)
> > [    0.097183] task: ffff80003e8c8b80 task.stack: ffff80003e8d0000
> > [    0.097197] PC is at gic_populate_rdist+0x74/0x15c
> > [    0.097202] LR is at gic_starting_cpu+0xc/0x20
> > [    0.097206] pc : [<ffff0000082b1b18>] lr : [<ffff0000082b26e0>] pstate: 600001c5
> > 
> > Signed-off-by: Jun Nie <[email-masked]>
> > ---
> >  arch/arm64/boot/dts/zte/zx296718.dtsi | 11 +++--------
> >  1 file changed, 3 insertions(+), 8 deletions(-)
> > 
> > diff --git a/arch/arm64/boot/dts/zte/zx296718.dtsi b/arch/arm64/boot/dts/zte/zx296718.dtsi
> > index a223066..6b239a3 100644
> > --- a/arch/arm64/boot/dts/zte/zx296718.dtsi
> > +++ b/arch/arm64/boot/dts/zte/zx296718.dtsi
> > @@ -239,16 +239,11 @@
> >  		compatible = "arm,gic-v3";
> >  		#interrupt-cells = <3>;
> >  		#address-cells = <0>;
> > -		#redistributor-regions = <6>;
> > -		redistributor-stride = <0x0 0x40000>;
> > +		#redistributor-regions = <1>;
> > +		redistributor-stride = <0x20000>;
> 
> Why is that stride specified? Is the GIC implementation so busted that
> the GICR_TYPER do not report a GICv3 redistributor, which implies a
> 128kB stride?

No, it's not required per my testing.  I guess it's there for
documentation purpose to make the stride setting explicit.  Are you
suggesting that we simply drop it?

Also, it seems that #redistributor-regions can also be saved, since
bindings doc tells that it's only required if more than one such region
is present?

Shawn