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

Jitao Shi
2020-02-25T11:42:58Z

On Wed, 2019-12-18 at 13:41 +0800, CK Hu wrote:
> 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
>

'MIPITX_VOLTAGE_SEL' is the whole 32bit name.
mipitx-current-drive is just bit[9:6] RG_DSI_HSTX_LDO_REF_SEL,

Not for voltage.

Best Regards
Jitao

> > 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 {
>
>