Re: [PATCH 1/4] dt-binds: display: mediatek: add property to control mipi tx drive current

CK Hu
2019-12-18T05:51:47Z

Hi, Jitao:

On Mon, 2019-12-16 at 16:29 +0800, Jitao Shi wrote:
> Add a property to control mipi tx drive current:
> "mipitx-current-drive"
>
> Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
> ---
> .../devicetree/bindings/display/mediatek/mediatek,dsi.txt | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt b/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
> index a19a6cc375ed..780201ddcd5c 100644
> --- a/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
> +++ b/Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt
> @@ -33,6 +33,9 @@ Required properties:
> - #clock-cells: must be <0>;
> - #phy-cells: must be <0>.
>
> +Optional properties:
> +- mipitx-current-drive: adjust driving current, should be 1 ~ 0xF
> +

In "[PATCH 3/4] drm/mediatek: add the mipitx driving control" [1], I see
that you actually control a register its name is MIPITX_VOLTAGE_SEL, so
I guess this control the voltage. If mipi_tx has the ability to control
the voltage, could we just treat mipi_tx as a regulator? For a
regulator, regulator-min-microvolt and regulator-max-microvolt would
limit the volt range and you could get it by
of_get_regulator_init_data(). If it actually control the current,
regulator-min-microamp and regulator-max-microamp could be used. I'm not
expert on this, so please give me more information on this.

[1]
http://lists.infradead.org/pipermail/linux-mediatek/2019-December/025638.html

Regards,
CK

> Example:
>
> mipi_tx0: mipi-dphy@10215000 {
> @@ -42,6 +45,7 @@ mipi_tx0: mipi-dphy@10215000 {
> clock-output-names = "mipi_tx0_pll";
> #clock-cells = <0>;
> #phy-cells = <0>;
> + mipitx-current-drive = <0x8>;
> };
>
> dsi0: dsi@1401b000 {