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

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Date:   Fri, 27 Jan 2017 14:30:01 -0600
From:   Rob Herring <robh@...nel.org>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Mark Rutland <mark.rutland@....com>,
        Tsahee Zidenberg <tsahee@...apurnalabs.com>,
        Antoine Tenart <antoine.tenart@...e-electrons.com>,
        Russell King <linux@...linux.org.uk>,
        Benoît Cousson <bcousson@...libre.com>,
        Tony Lindgren <tony@...mide.com>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Javier Martinez Canillas <javier@....samsung.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Fabio Estevam <fabio.estevam@....com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Simon Horman <horms@...ge.net.au>,
        Magnus Damm <magnus.damm@...il.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>, arm@...nel.org
Subject: Re: [PATCH v2 1/2] dt-bindings: arm,gic: Fix binding example for a
 virt-capable GIC

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@...mide.com>
> Acked-by: Mark Rutland <mark.rutland@....com>
> Acked-by: Arnd Bergmann <arnd@...db.de>
> Signed-off-by: Marc Zyngier <marc.zyngier@....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@...01000 {
> -		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.

Rob