Re: [PATCH v10, 15/19] dt-bindings: media: mtk-vcodec: Adds decoder dt-bindings for mt8192

From: Ezequiel Garcia
Date: Sun Nov 14 2021 - 16:57:13 EST

Yunfei,

On Thu, 11 Nov 2021 at 01:15, Yunfei Dong <yunfei.dong@xxxxxxxxxxxx> wrote:
>
> Adds decoder dt-bindings for mt8192.
>
> Signed-off-by: Yunfei Dong <yunfei.dong@xxxxxxxxxxxx>
> ---
> .../media/mediatek,vcodec-subdev-decoder.yaml | 261 ++++++++++++++++++
> 1 file changed, 261 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/media/mediatek,vcodec-subdev-decoder.yaml
>
> diff --git a/Documentation/devicetree/bindings/media/mediatek,vcodec-subdev-decoder.yaml b/Documentation/devicetree/bindings/media/mediatek,vcodec-subdev-decoder.yaml
> new file mode 100644
> index 000000000000..1886fae6e39d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/mediatek,vcodec-subdev-decoder.yaml
> @@ -0,0 +1,261 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +
> +%YAML 1.2
> +---
> +$id: "http://devicetree.org/schemas/media/mediatek,vcodec-subdev-decoder.yaml#";
> +$schema: "http://devicetree.org/meta-schemas/core.yaml#";
> +
> +title: Mediatek Video Decode Accelerator With Multi Hardware
> +
> +maintainers:
> + - Yunfei Dong <yunfei.dong@xxxxxxxxxxxx>
> +
> +description: |
> + Mediatek Video Decode is the video decode hardware present in Mediatek
> + SoCs which supports high resolution decoding functionalities. Required
> + main and subdev device node.
> +
> + About the Decoder Hardware Block Diagram, please check below:
> +
> + +---------------------------------+------------------------------------+
> + | | |
> + | input -> lat HW -> lat buffer --|--> lat buffer -> core HW -> output
|

To be completely honest, I can't really understand what is the meaning
of the blocks
with input -> lat hw -> lat buffer, and how this means lat- and core-
are children of some parent.

> + | || | || |
> + +------------||-------------------+---------------------||-------------+
> + || lat thread | core thread || <parent>
> + -------------||-----------------------------------------||----------------
> + || || <child>
> + \/ <----------------HW index-------------->\/
> + +------------------------------------------------------+
> + | enable/disable |
> + | clk power irq iommu port |
> + | (lat/lat soc/core0/core1) |
> + +------------------------------------------------------+
> +
> + As above, <parent> mean in main device, <child> mean in subdev device. The information
> + of each hardware will be stored in subdev device. There are two workqueues in main device:
> + lat and core. Enable/disable the lat clk/power/irq when lat need to work through hardware
> + index, core is the same.
> +
> + Normally the smi common may not the same for each hardware, can't combine all hardware in
> + one node, or leading to iommu fault when access dram data.
> +

To what extent the lat- and core- devices are really "children"
or "subdevices" of the video-codec@16000000 device?

I.e. what resources do they share? What are the details of
their bus topology?

> +
> +examples:
> + - |
> + #include <dt-bindings/interrupt-controller/arm-gic.h>
> + #include <dt-bindings/memory/mt8192-larb-port.h>
> + #include <dt-bindings/interrupt-controller/irq.h>
> + #include <dt-bindings/clock/mt8192-clk.h>
> + #include <dt-bindings/power/mt8192-power.h>
> +
> + video-codec@16000000 {
> + compatible = "mediatek,mt8192-vcodec-dec";
> + reg = <0x16000000 0x1000>; /* VDEC_SYS */
> + mediatek,scp = <&scp>;
> + iommus = <&iommu0 M4U_PORT_L4_VDEC_MC_EXT>;
> + dma-ranges = <0x1 0x0 0x0 0x40000000 0x0 0xfff00000>;
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges;
> + vcodec-lat@16010000 {
> + compatible = "mediatek,mtk-vcodec-lat";
> + reg = <0x16010000 0x800>;
> + interrupts = <GIC_SPI 426 IRQ_TYPE_LEVEL_HIGH 0>;
> + iommus = <&iommu0 M4U_PORT_L5_VDEC_LAT0_VLD_EXT>,
> + <&iommu0 M4U_PORT_L5_VDEC_LAT0_VLD2_EXT>,
> + <&iommu0 M4U_PORT_L5_VDEC_LAT0_AVC_MV_EXT>,
> + <&iommu0 M4U_PORT_L5_VDEC_LAT0_PRED_RD_EXT>,
> + <&iommu0 M4U_PORT_L5_VDEC_LAT0_TILE_EXT>,
> + <&iommu0 M4U_PORT_L5_VDEC_LAT0_WDMA_EXT>,
> + <&iommu0 M4U_PORT_L5_VDEC_LAT0_RG_CTRL_DMA_EXT>,
> + <&iommu0 M4U_PORT_L5_VDEC_UFO_ENC_EXT>;
> + clocks = <&topckgen CLK_TOP_VDEC_SEL>,
> + <&vdecsys_soc CLK_VDEC_SOC_VDEC>,
> + <&vdecsys_soc CLK_VDEC_SOC_LAT>,
> + <&vdecsys_soc CLK_VDEC_SOC_LARB1>,
> + <&topckgen CLK_TOP_MAINPLL_D4>;
> + clock-names = "sel", "soc-vdec", "soc-lat", "vdec", "top";
> + assigned-clocks = <&topckgen CLK_TOP_VDEC_SEL>;
> + assigned-clock-parents = <&topckgen CLK_TOP_MAINPLL_D4>;
> + power-domains = <&spm MT8192_POWER_DOMAIN_VDEC>;
> + };
> +
> + vcodec-core@16025000 {
> + compatible = "mediatek,mtk-vcodec-core";
> + reg = <0x16025000 0x1000>;

The children address space might need some thinking.
In other words,

video-codec@16000000 {

vcodec-lat@16010000 {
}

vcodec-core@16025000 {
}
}

Your proposal has vcodec-lat as children of video-codec, but its address space
are really on the same level, instead of children being contained in
the parent address space:

video-codec@16000000 {

vcodec-lat@10000 {
}

vcodec-core@25000 {
}
}

I think this last tree makes more sense from a device-tree point of view.
The ranges property allows you to put the right translation information,
so the device driver itself will get the correct address 0x16000000 + 0x25000.

You might find that the ranges property is tricky to understand at first.

Thanks,
Ezequiel


> + interrupts = <GIC_SPI 425 IRQ_TYPE_LEVEL_HIGH 0>;
> + iommus = <&iommu0 M4U_PORT_L4_VDEC_MC_EXT>,
> + <&iommu0 M4U_PORT_L4_VDEC_UFO_EXT>,
> + <&iommu0 M4U_PORT_L4_VDEC_PP_EXT>,
> + <&iommu0 M4U_PORT_L4_VDEC_PRED_RD_EXT>,
> + <&iommu0 M4U_PORT_L4_VDEC_PRED_WR_EXT>,
> + <&iommu0 M4U_PORT_L4_VDEC_PPWRAP_EXT>,
> + <&iommu0 M4U_PORT_L4_VDEC_TILE_EXT>,
> + <&iommu0 M4U_PORT_L4_VDEC_VLD_EXT>,
> + <&iommu0 M4U_PORT_L4_VDEC_VLD2_EXT>,
> + <&iommu0 M4U_PORT_L4_VDEC_AVC_MV_EXT>,
> + <&iommu0 M4U_PORT_L4_VDEC_RG_CTRL_DMA_EXT>;
> + clocks = <&topckgen CLK_TOP_VDEC_SEL>,
> + <&vdecsys CLK_VDEC_VDEC>,
> + <&vdecsys CLK_VDEC_LAT>,
> + <&vdecsys CLK_VDEC_LARB1>,
> + <&topckgen CLK_TOP_MAINPLL_D4>;
> + clock-names = "sel", "soc-vdec", "soc-lat", "vdec", "top";
> + assigned-clocks = <&topckgen CLK_TOP_VDEC_SEL>;
> + assigned-clock-parents = <&topckgen CLK_TOP_MAINPLL_D4>;
> + power-domains = <&spm MT8192_POWER_DOMAIN_VDEC2>;
> + };
> + };
> --
> 2.25.1
>