Re: [PATCH v2 1/2] dt-bindings: display: rockchip: Add compatible for rk3568 HDMI

[Michael Riesch <michael.riesch@wolfvision.net>]

Hello Benjamin,

The HDMI TX block in the RK3568 requires two power supplies, which have
to be enabled in some cases (at least on the RK3568 EVB1 the voltages
VDDA0V9_IMAGE and VCCA1V8_IMAGE are disabled by default). It would be
great if this was considered by the driver and the device tree binding.
I am not sure, though, whether this is a RK3568 specific or
rockchip_dw_hdmi specific thing. Maybe it can even enter the Synopsis DW
HDMI driver.

On 7/7/21 2:03 PM, Benjamin Gaignard wrote:
> Define a new compatible for rk3568 HDMI.
> This version of HDMI hardware block needs two new clocks hclk_vio and hclk
> to provide phy reference clocks.
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> ---
> version 2:
> - Add the clocks needed for the phy.
> 
>  .../bindings/display/rockchip/rockchip,dw-hdmi.yaml         | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/rockchip/rockchip,dw-hdmi.yaml b/Documentation/devicetree/bindings/display/rockchip/rockchip,dw-hdmi.yaml
> index 75cd9c686e985..cb8643b3a8b84 100644
> --- a/Documentation/devicetree/bindings/display/rockchip/rockchip,dw-hdmi.yaml
> +++ b/Documentation/devicetree/bindings/display/rockchip/rockchip,dw-hdmi.yaml
> @@ -23,6 +23,7 @@ properties:
>        - rockchip,rk3288-dw-hdmi
>        - rockchip,rk3328-dw-hdmi
>        - rockchip,rk3399-dw-hdmi
> +      - rockchip,rk3568-dw-hdmi
>  
>    reg-io-width:
>      const: 4
> @@ -51,8 +52,11 @@ properties:
>            - vpll
>        - enum:
>            - grf
> +          - hclk_vio
> +          - vpll
> +      - enum:
> +          - hclk
>            - vpll
> -      - const: vpll

The description and documentation of the clocks are somewhat misleading
IMHO. This is not caused by your patches, of course. But maybe this is a
chance to clean them up a bit.

It seems that the CEC clock is an optional clock of the dw-hdmi driver.
Shouldn't it be documented in the synopsys,dw-hdmi.yaml?

Also, it would be nice if the clocks hclk_vio and hclk featured a
description in the binding.

BTW, I am not too familiar with the syntax here, but shouldn't items in
clocks and items in clock-names be aligned (currently, there is a plain
list vs. an enum structure)?

Best regards,
Michael

>  
>    ddc-i2c-bus:
>      $ref: /schemas/types.yaml#/definitions/phandle
>