Re: [PATCH v7 01/12] dt-bindings: add img,pvrsgx.yaml for Imagination GPUs

From: Paul Cercueil <paul@crapouillou.net>
To: "H. Nikolaus Schaller" <hns@goldelico.com>
Cc: "David Airlie" <airlied@linux.ie>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Benoît Cousson" <bcousson@baylibre.com>,
	"Tony Lindgren" <tony@atomide.com>,
	"Ralf Baechle" <ralf@linux-mips.org>,
	"Paul Burton" <paulburton@kernel.org>,
	"James Hogan" <jhogan@kernel.org>,
	"Kukjin Kim" <kgene@kernel.org>,
	"Krzysztof Kozlowski" <krzk@kernel.org>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Chen-Yu Tsai" <wens@csie.org>,
	"Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
	"Jonathan Bakker" <xc-racer2@live.ca>,
	"Philipp Rossak" <embed3d@gmail.com>,
	dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org,
	openpvrsgx-devgroup@letux.org, letux-kernel@openphoenux.org,
	kernel@pyra-handheld.com, linux-mips@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org
Subject: Re: [PATCH v7 01/12] dt-bindings: add img,pvrsgx.yaml for Imagination GPUs
Date: Sun, 26 Apr 2020 15:11:11 +0200	[thread overview]
Message-ID: <NMCE9Q.LWG45P20NBVJ@crapouillou.net> (raw)
In-Reply-To: <3a451e360fed84bc40287678b4d6be13821cfbc0.1587760454.git.hns@goldelico.com>

Hi Nikolaus,

Le ven. 24 avril 2020 à 22:34, H. Nikolaus Schaller 
<hns@goldelico.com> a écrit :
> The Imagination PVR/SGX GPU is part of several SoC from
> multiple vendors, e.g. TI OMAP, Ingenic JZ4780, Intel Poulsbo,
> Allwinner A83 and others.
> 
> With this binding, we describe how the SGX processor is
> interfaced to the SoC (registers and interrupt).
> 
> The interface also consists of clocks, reset, power but
> information from data sheets is vague and some SoC integrators
> (TI) deciced to use a PRCM wrapper (ti,sysc) which does
> all clock, reset and power-management through registers
> outside of the sgx register block.
> 
> Therefore all these properties are optional.
> 
> Tested by make dt_binding_check
> 
> Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
> ---
>  .../devicetree/bindings/gpu/img,pvrsgx.yaml   | 150 
> ++++++++++++++++++
>  1 file changed, 150 insertions(+)
>  create mode 100644 
> Documentation/devicetree/bindings/gpu/img,pvrsgx.yaml
> 
> diff --git a/Documentation/devicetree/bindings/gpu/img,pvrsgx.yaml 
> b/Documentation/devicetree/bindings/gpu/img,pvrsgx.yaml
> new file mode 100644
> index 000000000000..33a9c4c6e784
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpu/img,pvrsgx.yaml
> @@ -0,0 +1,150 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/gpu/img,pvrsgx.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Imagination PVR/SGX GPU
> +
> +maintainers:
> +  - H. Nikolaus Schaller <hns@goldelico.com>
> +
> +description: |+
> +  This binding describes the Imagination SGX5 series of 3D 
> accelerators which
> +  are found in several different SoC like TI OMAP, Sitara, Ingenic 
> JZ4780,
> +  Allwinner A83, and Intel Poulsbo and CedarView and more.
> +
> +  For an extensive list see: 
> https://en.wikipedia.org/wiki/PowerVR#Implementations
> +
> +  The SGX node is usually a child node of some DT node belonging to 
> the SoC
> +  which handles clocks, reset and general address space mapping of 
> the SGX
> +  register area. If not, an optional clock can be specified here.
> +
> +properties:
> +  $nodename:
> +    pattern: '^gpu@[a-f0-9]+$'
> +  compatible:
> +    oneOf:
> +      - description: SGX530-121 based SoC
> +        items:
> +          - enum:
> +            - ti,omap3-sgx530-121 # BeagleBoard A/B/C, OpenPandora 
> 600MHz and similar
> +          - const: img,sgx530-121
> +          - const: img,sgx530
> +
> +      - description: SGX530-125 based SoC
> +        items:
> +          - enum:
> +            - ti,am3352-sgx530-125 # BeagleBone Black
> +            - ti,am3517-sgx530-125
> +            - ti,am4-sgx530-125
> +            - ti,omap3-sgx530-125 # BeagleBoard XM, GTA04, 
> OpenPandora 1GHz and similar
> +            - ti,ti81xx-sgx530-125
> +          - const: ti,omap3-sgx530-125
> +          - const: img,sgx530-125
> +          - const: img,sgx530
> +
> +      - description: SGX535-116 based SoC
> +        items:
> +          - const: intel,poulsbo-gma500-sgx535 # Atom Z5xx
> +          - const: img,sgx535-116
> +          - const: img,sgx535
> +
> +      - description: SGX540-116 based SoC
> +        items:
> +          - const: intel,medfield-gma-sgx540 # Atom Z24xx
> +          - const: img,sgx540-116
> +          - const: img,sgx540
> +
> +      - description: SGX540-120 based SoC
> +        items:
> +          - enum:
> +            - samsung,s5pv210-sgx540-120
> +            - ti,omap4-sgx540-120 # Pandaboard, Pandaboard ES and 
> similar
> +          - const: img,sgx540-120
> +          - const: img,sgx540
> +
> +      - description: SGX540-130 based SoC
> +        items:
> +          - enum:
> +            - ingenic,jz4780-sgx540-130 # CI20
> +          - const: img,sgx540-130
> +          - const: img,sgx540
> +
> +      - description: SGX544-112 based SoC
> +        items:
> +          - const: ti,omap4470-sgx544-112
> +          - const: img,sgx544-112
> +          - const: img,sgx544
> +
> +      - description: SGX544-115 based SoC
> +        items:
> +          - enum:
> +            - allwinner,sun8i-a31-sgx544-115
> +            - allwinner,sun8i-a31s-sgx544-115
> +            - allwinner,sun8i-a83t-sgx544-115 # Banana-Pi-M3 
> (Allwinner A83T) and similar
> +          - const: img,sgx544-115
> +          - const: img,sgx544
> +
> +      - description: SGX544-116 based SoC
> +        items:
> +          - enum:
> +            - ti,dra7-sgx544-116 # DRA7
> +            - ti,omap5-sgx544-116 # OMAP5 UEVM, Pyra Handheld and 
> similar
> +          - const: img,sgx544-116
> +          - const: img,sgx544
> +
> +      - description: SGX545 based SoC
> +        items:
> +          - const: intel,cedarview-gma3600-sgx545 # Atom N2600, D2500
> +          - const: img,sgx545-116
> +          - const: img,sgx545
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  interrupt-names:
> +    maxItems: 1
> +    items:
> +      - const: sgx
> +
> +  clocks:
> +    maxItems: 4
> +
> +  clock-names:
> +    maxItems: 4
> +    items:
> +      - const: core
> +      - const: sys
> +      - const: mem
> +      - const: hyd
> +
> +  sgx-supply: true
> +
> +  power-domains:
> +    maxItems: 1
> +
> +  resets:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts

By not making 'clocks' required you make it possible to create broken 
bindings; according to your schema, a GPU node without a 'clocks' for 
the JZ4780 would be perfectly valid.

It's possible to forbid the presence of the 'clocks' property on some 
implementations, and require it on others.
See how it's done for instance on 
Documentation/devicetree/bindings/serial/samsung_uart.yaml.

-Paul

> +
> +additionalProperties: false
> +
> +examples:
> +  - |+
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> +    gpu: gpu@fe00 {
> +      compatible = "ti,omap5-sgx544-116", "img,sgx544-116", 
> "img,sgx544";
> +      reg = <0xfe00 0x200>;
> +      interrupts = <GIC_SPI 21 IRQ_TYPE_LEVEL_HIGH>;
> +    };
> +
> +...
> --
> 2.25.1
> 