Re: [PATCH v8 2/3] MIPS: Loongson64: dts: update the display controller device node

[Krzysztof Kozlowski]

On 16/02/2022 19:17, Sui Jingfeng wrote:
> From: suijingfeng <suijingfeng@xxxxxxxxxxx>
> 
> The display controller is a pci device, its PCI vendor id is 0x0014
> its PCI device id is 0x7a06.
> 
> 1) In order to let the lsdc kms driver to know which chip the DC is
>    contained in, we add different compatible for different chip.
> 
> 2) Add display controller device node for ls2k1000 SoC
> 
> Signed-off-by: suijingfeng <suijingfeng@xxxxxxxxxxx>
> Signed-off-by: Sui Jingfeng <15330273260@xxxxxx>
> ---
>  .../loongson/loongson,display-controller.yaml | 114 ++++++++++++++++++
>  .../display/loongson/loongson-drm.txt         |  16 +++

Please split dt-bindings from other changes into a separate patch, which
should be first in the series.

>  .../boot/dts/loongson/loongson64-2k1000.dtsi  |   8 ++
>  arch/mips/boot/dts/loongson/ls7a-pch.dtsi     |   7 +-
>  4 files changed, 140 insertions(+), 5 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/display/loongson/loongson,display-controller.yaml
>  create mode 100644 Documentation/devicetree/bindings/display/loongson/loongson-drm.txt
> 
> diff --git a/Documentation/devicetree/bindings/display/loongson/loongson,display-controller.yaml b/Documentation/devicetree/bindings/display/loongson/loongson,display-controller.yaml
> new file mode 100644
> index 000000000000..64d8364b50ab
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/loongson/loongson,display-controller.yaml
> @@ -0,0 +1,114 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/pci0014,7a06.yaml#

The file name looks different than ID. Does this pass `make
dt_binding_check` validation?

> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Loongson LS7A2000/LS7A1000/LS2K1000/LS2K0500 Display Controller Device Tree Bindings
> +
> +maintainers:
> +  - Sui Jingfeng <suijingfeng@xxxxxxxxxxx>
> +
> +description: |+
> +
> +  Loongson display controllers are simple which require scanout buffers
> +  to be physically contiguous. LS2K1000/LS2K0500 is a SOC, only system
> +  memory is available. LS7A1000/LS7A2000 is bridge chip which is equipped
> +  with a dedicated video ram which is 64MB or more.
> +
> +  For LS7A1000, there are 4 dedicated GPIOs whose control register is
> +  located at the DC register space. They are used to emulate two way i2c,
> +  One for DVO0, another for DVO1.
> +
> +  LS2K1000 and LS2K0500 SoC grab i2c adapter from other module, either
> +  general purpose GPIO emulated i2c or hardware i2c in the SoC.
> +
> +  LSDC has two display pipes, each way has a DVO interface which provide
> +  RGB888 signals, vertical & horizontal synchronisations, data enable and
> +  the pixel clock. LSDC has two CRTC, each CRTC is able to scanout from
> +  1920x1080 resolution at 60Hz. Each CRTC has two FB address registers.
> +
> +  LSDC's display pipeline have several components as below description,
> +
> +  The display controller in LS7A1000:
> +    ___________________                                     _________
> +    |            -------|                                   |         |
> +    |  CRTC0 --> | DVO0 ----> Encoder0 ---> Connector0 ---> | Monotor |
> +    |  _   _     -------|        ^             ^            |_________|
> +    | | | | |    -------|        |             |
> +    | |_| |_|    | i2c0 <--------+-------------+
> +    |            -------|
> +    |   DC IN LS7A1000  |
> +    |  _   _     -------|
> +    | | | | |    | i2c1 <--------+-------------+
> +    | |_| |_|    -------|        |             |             _________
> +    |            -------|        |             |            |         |
> +    |  CRTC1 --> | DVO1 ----> Encoder1 ---> Connector1 ---> |  Panel  |
> +    |            -------|                                   |_________|
> +    |___________________|
> +
> +  Simple usage of LS7A1000 with LS3A4000 CPU:
> +
> +    +------+            +-----------------------------------+
> +    | DDR4 |            |  +-------------------+            |
> +    +------+            |  | PCIe Root complex |   LS7A1000 |
> +       || MC0           |  +--++---------++----+            |
> +  +----------+  HT 3.0  |     ||         ||                 |
> +  | LS3A4000 |<-------->| +---++---+  +--++--+    +---------+   +------+
> +  |   CPU    |<-------->| | GC1000 |  | LSDC |<-->| DDR3 MC |<->| VRAM |
> +  +----------+          | +--------+  +-+--+-+    +---------+   +------+
> +       || MC1           +---------------|--|----------------+
> +    +------+                            |  |
> +    | DDR4 |          +-------+   DVO0  |  |  DVO1   +------+
> +    +------+   VGA <--|ADV7125|<--------+  +-------->|TFP410|--> DVI/HDMI
> +                      +-------+                      +------+
> +
> +  The display controller in LS2K1000/LS2K0500:
> +     ___________________                                     _________
> +    |            -------|                                   |         |
> +    |  CRTC0 --> | DVO0 ----> Encoder0 ---> Connector0 ---> | Monotor |
> +    |  _   _     -------|        ^              ^           |_________|
> +    | | | | |           |        |              |
> +    | |_| |_|           |     +------+          |
> +    |                   <---->| i2c0 |<---------+
> +    |   DC IN LS2K1000  |     +------+
> +    |  _   _            |     +------+
> +    | | | | |           <---->| i2c1 |----------+
> +    | |_| |_|           |     +------+          |            _________
> +    |            -------|        |              |           |         |
> +    |  CRTC1 --> | DVO1 ----> Encoder1 ---> Connector1 ---> |  Panel  |
> +    |            -------|                                   |_________|
> +    |___________________|
> +
> +properties:
> +  compatible:
> +    enum:
> +      - loongson,ls7a2000-dc
> +      - loongson,ls7a1000-dc
> +      - loongson,ls2k1000-dc
> +      - loongson,ls2k0500-dc
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    minItems: 1

You need also maxItems. If you have only one interrupt, then just
maxItems:1.

> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    lsdc: dc@6,1 {

node name should be generic: "display-controller"

The unit address does not look like matching the reg property. Is this
how it suppose to be?

> +        compatible = "loongson,ls7a1000-dc";
> +        reg = <0x3100 0x0 0x0 0x0 0x0>;
> +        interrupts = <28 IRQ_TYPE_LEVEL_HIGH>;
> +        interrupt-parent = <&pic>;
> +    };
> +
> +...


Best regards,
Krzysztof