linux-kernel - RE: [EXT] Re: [v2 1/4] dt-bindings: display: Add DT bindings for LS1028A HDP-TX PHY.

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Date:   Tue, 13 Aug 2019 02:34:55 +0000
From:   Wen He <wen.he_1@....com>
To:     Rob Herring <robh@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        Leo Li <leoyang.li@....com>
Subject: RE: [EXT] Re: [v2 1/4] dt-bindings: display: Add DT bindings for
 LS1028A HDP-TX PHY.



> -----Original Message-----
> From: Rob Herring <robh@...nel.org>
> Sent: 2019年8月13日 7:30
> To: Wen He <wen.he_1@....com>
> Cc: linux-kernel@...r.kernel.org; dri-devel@...ts.freedesktop.org;
> devicetree@...r.kernel.org; mark.rutland@....com; shawnguo@...nel.org;
> Leo Li <leoyang.li@....com>
> Subject: [EXT] Re: [v2 1/4] dt-bindings: display: Add DT bindings for LS1028A
> HDP-TX PHY.
> 
> Caution: EXT Email
> 
> On Fri, Jul 19, 2019 at 06:09:39PM +0800, Wen He wrote:
> > Add DT bindings documentmation for the HDP-TX PHY controller. The
> > describes which could be found on NXP Layerscape ls1028a platform.
> 
> Not required, but please consider converting to DT schema (YAML) format.

Understand,

> 
> >
> > Signed-off-by: Wen He <wen.he_1@....com>
> > ---
> > change in v2:
> >         - correction the node name.
> >
> >  .../devicetree/bindings/display/fsl,hdp.txt   | 56 +++++++++++++++++++
> >  1 file changed, 56 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/display/fsl,hdp.txt
> >
> > diff --git a/Documentation/devicetree/bindings/display/fsl,hdp.txt
> > b/Documentation/devicetree/bindings/display/fsl,hdp.txt
> > new file mode 100644
> > index 000000000000..53ca08337587
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/display/fsl,hdp.txt
> > @@ -0,0 +1,56 @@
> > +NXP Layerscpae ls1028a HDP-TX PHY Controller
> 
> typo
> 
> > +============================================
> > +
> > +The following bindings describe the Cadence HDP TX PHY on ls1028a
> > +that offer multi-protocol support of standars such as eDP and
> > +Displayport,
> 
> s/offer/offers/
> 
> and another typo.
> 
> > +supports for 25-600MHz pixel clock and up to 4k2k at 60MHz resolution.
> > +The HDP transmitter is a Cadence HDP TX controller IP with a
> > +companion PHY IP.
> > +
> > +Required properties:
> > +  - compatible:   Should be "fsl,ls1028a-dp" for ls1028a.
> > +  - reg:          Physical base address and size of the block of registers
> used
> > +  by the processor.
> 
> The example shows 2 regions, what are they?

One is HDP transmitter controller address region, another is multimedia PLL address region.
Sorry, here should be use the HDP transmitter controller region. 

I've already send clock patches included the multimedia PLL implementation.

> 
> > +  - interrupts:   HDP hotplug in/out detect interrupt number
> > +  - clocks:       A list of phandle + clock-specifier pairs, one for each
> entry
> > +  in 'clock-names'
> > +  - clock-names:  A list of clock names. It should contain:
> > +      - "clk_ipg": inter-Integrated circuit clock
> > +      - "clk_core": for the Main Display TX controller clock
> > +      - "clk_pxl": for the pixel clock feeding the output PLL of the processor
> > +      - "clk_pxl_mux": for the high PerfPLL bypass clock
> > +      - "clk_pxl_link": for the link rate pixel clock
> > +      - "clk_apb": for the APB interface clock
> > +      - "clk_vif": for the Video pixel clock
> 
> 'clk_' is redundant.
> 

OK

> > +
> > +Required sub-nodes:
> > +  - port: The HDP connection to an encoder output port. The connection
> > +    is modelled using the OF graph bindings specified in
> > +    Documentation/devicetree/bindings/graph.txt
> 
> I'm still confused as to what this block does? The 'encoder output' is
> DisplayPort? If this is just a phy, then use the phy binding.
> 
> Normally, a DisplayPort encoder/bridge OF graph output would be connected
> to a DP connector node or a panel.

Yes, you are right, but 
For LS1028A, HDP(Cadence HD Display Transmitter) are included eDP/Display port controller and Display PHY controller.
In other word, they are 1 IP block on LS1028A.

A full graphics connection relationship of the LS1028A:

DP500 --> eDP/DP controller ---> DPHY ---> DP/eDP interface.

Best Regards,
Wen

> 
> Rob