Re: [PATCH v2 08/10] dt-bindings: media: Document bindings for the Sunxi-Cedrus VPU driver

[Philipp Zabel <p.zabel@pengutronix.de>]

Hi Paul,

On Thu, 2018-04-19 at 17:45 +0200, Paul Kocialkowski wrote:
> This adds a device-tree binding document that specifies the properties
> used by the Sunxi-Cedurs VPU driver, as well as examples.
> 
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> ---
>  .../devicetree/bindings/media/sunxi-cedrus.txt     | 50 ++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/sunxi-cedrus.txt
> 
> diff --git a/Documentation/devicetree/bindings/media/sunxi-cedrus.txt b/Documentation/devicetree/bindings/media/sunxi-cedrus.txt
> new file mode 100644
> index 000000000000..71ad3f9c3352
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/sunxi-cedrus.txt
> @@ -0,0 +1,50 @@
> +Device-tree bindings for the VPU found in Allwinner SoCs, referred to as the
> +Video Engine (VE) in Allwinner literature.
> +
> +The VPU can only access the first 256 MiB of DRAM, that are DMA-mapped starting
> +from the DRAM base. This requires specific memory allocation and handling.
> +
> +Required properties:
> +- compatible	        : "allwinner,sun4i-a10-video-engine";
> +- memory-region         : DMA pool for buffers allocation;
> +- clocks	        : list of clock specifiers, corresponding to entries in
> +                          the clock-names property;
> +- clock-names	        : should contain "ahb", "mod" and "ram" entries;
> +- assigned-clocks       : list of clocks assigned to the VE;
> +- assigned-clocks-rates : list of clock rates for the clocks assigned to the VE;
> +- resets	        : phandle for reset;
> +- interrupts	        : should contain VE interrupt number;
> +- reg		        : should contain register base and length of VE.
> +
> +Example:
> +
> +reserved-memory {
> +	#address-cells = <1>;
> +	#size-cells = <1>;
> +	ranges;
> +
> +	/* Address must be kept in the lower 256 MiBs of DRAM for VE. */
> +	ve_memory: cma@4a000000 {
> +		compatible = "shared-dma-pool";
> +		reg = <0x4a000000 0x6000000>;
> +		no-map;
> +		linux,cma-default;
> +	};
> +};
> +
> +video-engine@1c0e000 {

This is not really required by any specification, and not as common as
gpu@..., but could this reasonably be called "vpu@1c0e000" to follow
somewhat-common practice?

> +	compatible = "allwinner,sun4i-a10-video-engine";
> +	reg = <0x01c0e000 0x1000>;
> +	memory-region = <&ve_memory>;
> +
> +	clocks = <&ccu CLK_AHB_VE>, <&ccu CLK_VE>,
> +		 <&ccu CLK_DRAM_VE>;
> +	clock-names = "ahb", "mod", "ram";
> +
> +	assigned-clocks = <&ccu CLK_VE>;
> +	assigned-clock-rates = <320000000>;
> +
> +	resets = <&ccu RST_VE>;
> +
> +	interrupts = <GIC_SPI 53 IRQ_TYPE_LEVEL_HIGH>;
> +};

regards
Philipp