linux-kernel - Re: [PATCH v6 1/4] dt-bindings: display: mediatek: update dpi supported chips

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Date:   Tue, 25 Feb 2020 10:13:56 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Jitao Shi <jitao.shi@...iatek.com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>, <yingjoe.chen@...iatek.com>,
        <eddie.huang@...iatek.com>, <cawa.cheng@...iatek.com>,
        <bibby.hsieh@...iatek.com>, <stonea168@....com>,
        <huijuan.xie@...iatek.com>
Subject: Re: [PATCH v6 1/4] dt-bindings: display: mediatek: update dpi
 supported chips

Hi, Jitao:

On Tue, 2020-02-25 at 10:05 +0800, Jitao Shi wrote:
> On Mon, 2020-02-24 at 16:46 +0800, CK Hu wrote:
> > Hi, Jitao:
> > 
> > On Fri, 2020-02-21 at 19:28 +0800, Jitao Shi wrote:
> > > Add decriptions about supported chips, including MT2701 & MT8173 &
> > > mt8183
> > > 
> > > 1. Add more chips support. ex. MT2701 & MT8173 & MT8183
> > > 2. Add property "dpi_pin_mode_swap" and "pinctrl-names" gpio mode dpi mode and
> > >    gpio oupput-low to avoid leakage current.
> > > 3. Add property "dpi_dual_edge" to config the dpi pin output mode dual edge or
> > >    single edge sample data.
> > > 
> > > Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
> > > ---
> > >  .../bindings/display/mediatek/mediatek,dpi.txt        | 11 +++++++++++
> > >  1 file changed, 11 insertions(+)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/display/mediatek/mediatek,dpi.txt b/Documentation/devicetree/bindings/display/mediatek/mediatek,dpi.txt
> > > index b6a7e7397b8b..cd6a1469c8b7 100644
> > > --- a/Documentation/devicetree/bindings/display/mediatek/mediatek,dpi.txt
> > > +++ b/Documentation/devicetree/bindings/display/mediatek/mediatek,dpi.txt
> > > @@ -7,6 +7,7 @@ output bus.
> > >  
> > >  Required properties:
> > >  - compatible: "mediatek,<chip>-dpi"
> > > +  the supported chips are mt2701 , mt8173 and mt8183.
> > >  - reg: Physical base address and length of the controller's registers
> > >  - interrupts: The interrupt signal from the function block.
> > >  - clocks: device clocks
> > > @@ -16,6 +17,11 @@ Required properties:
> > >    Documentation/devicetree/bindings/graph.txt. This port should be connected
> > >    to the input port of an attached HDMI or LVDS encoder chip.
> > >  
> > > +Optional properties:
> > > +- dpi_pin_mode_swap: Swap the pin mode between dpi mode and gpio mode.
> > > +- pinctrl-names: Contain "gpiomode" and "dpimode".
> > > +- dpi_dual_edge: Control the RGB 24bit data on 12 pins or 24 pins.
> > 
> > I've find that in [1], there are already a property of "pclk-sample"
> > which like this, but it only have rising (1) or falling (0) status. Does
> > that property describe the same thing with this property? If they are
> > the same, I think you should add new state, dual (2), for "pclk-sample".
> > 
> > [1]
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/media/video-interfaces.txt?h=v5.6-rc3
> > 
> > Regards,
> > CK
> > 
> 
> pclk-sample has two properties  rising or falling.
> It means to sample on rising or falling edge.
> 
> But, dpi_dual_edge means to sample on both rising and falling edge.
> 

It seems that both describe "When to sample data", so they are the same
for me.

I think we should prevent to invent a new property if there is already a
one. Even though pclk-sample just have two state (rising or falling
edge), I think we could add a new state (dual edge) to pclk-sample. 

Regards,
CK

> Best Regards
> Jitao
> > > +
> > >  Example:
> > >  
> > >  dpi0: dpi@...1d000 {
> > > @@ -26,6 +32,11 @@ dpi0: dpi@...1d000 {
> > >  		 <&mmsys CLK_MM_DPI_ENGINE>,
> > >  		 <&apmixedsys CLK_APMIXED_TVDPLL>;
> > >  	clock-names = "pixel", "engine", "pll";
> > > +	dpi_dual_edge;
> > > +	dpi_pin_mode_swap;
> > > +	pinctrl-names = "gpiomode", "dpimode";
> > > +	pinctrl-0 = <&dpi_pin_gpio>;
> > > +	pinctrl-1 = <&dpi_pin_func>;
> > >  
> > >  	port {
> > >  		dpi0_out: endpoint {
> > 
> > 
> 
>