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

From: Jitao Shi <jitao.shi@mediatek.com>
To: CK Hu <ck.hu@mediatek.com>
Cc: "Bibby Hsieh (謝濟遠)" <Bibby.Hsieh@mediatek.com>,
	srv_heupstream <srv_heupstream@mediatek.com>,
	"David Airlie" <airlied@linux.ie>,
	"stonea168@163.com" <stonea168@163.com>,
	"Cawa Cheng (鄭曄禧)" <cawa.cheng@mediatek.com>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"Sj Huang (黃信璋)" <sj.huang@mediatek.com>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"Yingjoe Chen (陳英洲)" <Yingjoe.Chen@mediatek.com>,
	"Eddie Huang (黃智傑)" <eddie.huang@mediatek.com>
Subject: Re: [PATCH 1/4] dt-binds: display: mediatek: add property to control mipi tx drive current
Date: Tue, 25 Feb 2020 19:42:35 +0800	[thread overview]
Message-ID: <1582630955.13085.2.camel@mszsdaap41> (raw)
In-Reply-To: <1576647693.15003.11.camel@mtksdaap41>

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 {
> 
> 

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