[PATCH v22 1/4] dt-bindings: soc: Add documentation for the MediaTek GCE unit

Rob Herring
2018-07-03T02:30:40Z

On Wed, Jun 27, 2018 at 07:16:09PM +0800, Houlong Wei wrote:
> This adds documentation for the MediaTek Global Command Engine (GCE) unit
> found in MT8173 SoCs.
>
> Signed-off-by: Houlong Wei <houlong.wei@mediatek.com>
> Signed-off-by: HS Liao <hs.liao@mediatek.com>
> ---
> Hi Rob,
> I don't add your ACK in this version since the dt-binding description
> has been changed. Thanks.
> ---
> .../devicetree/bindings/mailbox/mtk-gce.txt | 65 ++++++++++++++++++++
> include/dt-bindings/gce/mt8173-gce.h | 48 +++++++++++++++
> 2 files changed, 113 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/mailbox/mtk-gce.txt
> create mode 100644 include/dt-bindings/gce/mt8173-gce.h
>
> diff --git a/Documentation/devicetree/bindings/mailbox/mtk-gce.txt b/Documentation/devicetree/bindings/mailbox/mtk-gce.txt
> new file mode 100644
> index 0000000..26f65a4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mailbox/mtk-gce.txt
> @@ -0,0 +1,65 @@
> +MediaTek GCE
> +===============
> +
> +The Global Command Engine (GCE) is used to help read/write registers with
> +critical time limitation, such as updating display configuration during the
> +vblank. The GCE can be used to implement the Command Queue (CMDQ) driver.
> +
> +CMDQ driver uses mailbox framework for communication. Please refer to
> +mailbox.txt for generic information about mailbox device-tree bindings.
> +
> +Required properties:
> +- compatible: Must be "mediatek,mt8173-gce"
> +- reg: Address range of the GCE unit
> +- interrupts: The interrupt signal from the GCE block
> +- clock: Clocks according to the common clock binding
> +- clock-names: Must be "gce" to stand for GCE clock
> +- thread-num: Maximum threads count of GCE.

mediatek,thread-num

Is this needed for anything other than error checking the thread id in
the mbox cells? if that's it, then drop it.

> +- #mbox-cells: Should be 4.
> + <&phandle channel timeout priority atomic_exec>
> + phandle: Label name of a gce node.
> + channel: Channel of mailbox. Be equal to the thread id of GCE.
> + timeout: Maximum time of software waiting GCE processing done, in unit
> + of millisecond.
> + priority: Priority of GCE thread.
> + atomic_exec: GCE processing continuous packets of commands in atomic
> + way.
> +
> +Required properties for a client device:
> +- mboxes: Client use mailbox to communicate with GCE, it should have this
> + property and list of phandle, mailbox specifiers.
> +- gce-subsys: Specify the sub-system id which is corresponding to the register
> + address.

What is this for?

> +
> +Optional properties for a client device:
> +- gce-event: Specify the event if the client has any. Because the event is
> + parsed by client, so client can replace 'gce-event' with other meaningful
> + name.

If the client sets the name, then no point having here. It must be
documented in the client binding. But then, what is this for in the
first place?

> +
> +Some vaules of properties are defined in 'dt-bindings/gce/mt8173-gce.h'. Such as
> +thread number, sub-system ids, thread priority, event ids.
> +
> +Example:
> +
> + gce: gce at 10212000 {

mailbox at ...

> + compatible = "mediatek,mt8173-gce";
> + reg = <0 0x10212000 0 0x1000>;
> + interrupts = <GIC_SPI 135 IRQ_TYPE_LEVEL_LOW>;
> + clocks = <&infracfg CLK_INFRA_GCE>;
> + clock-names = "gce";
> + thread-num = CMDQ_THR_MAX_COUNT;
> + #mbox-cells = <4>;
> + };
> +
> +Example for a client device:
> +
> + mmsys: clock-controller at 14000000 {
> + compatible = "mediatek,mt8173-mmsys";
> + mboxes = <&gce 0 2000 CMDQ_THR_PRIO_LOWEST 1>,
> + <&gce 1 2000 CMDQ_THR_PRIO_LOWEST 1>;
> + gce-subsys = <SUBSYS_1400XXXX>;
> + mutex-event-eof = <CMDQ_EVENT_MUTEX0_STREAM_EOF
> + CMDQ_EVENT_MUTEX1_STREAM_EOF>;
> +
> + ...
> + };