Re: [PATCH v2 1/2] dt-bindings: arm,gic: Fix binding example for a virt-capable GIC

From: Olof Johansson <olof@lixom.net>
To: Rob Herring <robh@kernel.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Jason Cooper <jason@lakedaemon.net>,
	Mark Rutland <mark.rutland@arm.com>,
	Tsahee Zidenberg <tsahee@annapurnalabs.com>,
	Antoine Tenart <antoine.tenart@free-electrons.com>,
	Russell King <linux@armlinux.org.uk>,
	Beno?t Cousson <bcousson@baylibre.com>,
	Tony Lindgren <tony@atomide.com>, Kukjin Kim <kgene@kernel.org>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Javier Martinez Canillas <javier@osg.samsung.com>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <kernel@pengutronix.de>,
	Fabio Estevam <fabio.estevam@nxp.com>,
	Santosh Shilimkar <ssantosh@kernel.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Simon Horman <horms@verge.net.au>,
	Magnus Damm <magnus.damm@gmail.com>,
	Heiko Stuebner <heiko@sntech.de>,
	Maxime Ripard <maxime.ripard@free-electrons.com>,
	Chen-Yu Tsai <wens@csie.org>,
	arm@kernel.org
Subject: Re: [PATCH v2 1/2] dt-bindings: arm,gic: Fix binding example for a virt-capable GIC
Date: Sun, 29 Jan 2017 14:51:29 -0800	[thread overview]
Message-ID: <20170129225129.GK3133@localhost> (raw)
In-Reply-To: <20170127203001.qvlgzzrh5hx2pykf@rob-hp-laptop>

On Fri, Jan 27, 2017 at 02:30:01PM -0600, Rob Herring wrote:
> On Mon, Jan 23, 2017 at 03:56:13PM +0000, Marc Zyngier wrote:
> > The joys of copy/paste: the example of a virtualization capable GIC
> > in the DT binding was wrong, and propagated to dozens of platforms.
> > By having a GICC region that is only 4kB (instead of 8kB), we
> > end-up not being able to access the GICC_DIR register which is on
> > the second page.
> > 
> > Oh well. Let's fix the source of the crap before tackling individual
> > offenders. While we're at it, also fix the compatibility string to
> > mention "arm,gic-400", which is the name of the actual implementation
> > of the GICv2 spec.
> 
> "While we're at it", code for should be in a separate patch. :) I 
> wouldn't really care here, but you are not fixing anything...
> 
> > 
> > Acked-by: Tony Lindgren <tony@atomide.com>
> > Acked-by: Mark Rutland <mark.rutland@arm.com>
> > Acked-by: Arnd Bergmann <arnd@arndb.de>
> > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> > ---
> >  Documentation/devicetree/bindings/interrupt-controller/arm,gic.txt | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/interrupt-controller/arm,gic.txt b/Documentation/devicetree/bindings/interrupt-controller/arm,gic.txt
> > index 5393e2a..a3d51ed 100644
> > --- a/Documentation/devicetree/bindings/interrupt-controller/arm,gic.txt
> > +++ b/Documentation/devicetree/bindings/interrupt-controller/arm,gic.txt
> > @@ -107,11 +107,11 @@ Required properties:
> >  Example:
> >  
> >  	interrupt-controller@2c001000 {
> > -		compatible = "arm,cortex-a15-gic";
> > +		compatible = "arm,gic-400";
> 
> Which one is correct really depends on the platform. The A15 can have an 
> internal or external (gic-400) GIC. The former string is correct for an 
> A15 with an internal GIC. One such platform is Calxeda midway.
> 
> Arguably, we should not have arm,gic-400 by itself, but have an SoC 
> specific compatible in case it was integrated in interesting ways.

Good point (and thanks for bringing it up).

Marc, based on this; want to back the above out so we can apply the rest for
now, while you battle on the compatible details? :)

-Olof