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Message-ID: <1537954469.18381.0.camel@mtkswgap22>
Subject: Re: [Resend PATCH 5/5] arm: dts: mt7623: add display subsystem
 related device nodes
From:   Ryder Lee <ryder.lee@mediatek.com>
To:     Matthias Brugger <matthias.bgg@gmail.com>
CC:     CK Hu <ck.hu@mediatek.com>, Rob Herring <robh+dt@kernel.org>,
        Sean Wang <sean.wang@mediatek.com>,
        Roy Luo <cheng-hao.luo@mediatek.com>,
        Weijie Gao <weijie.gao@mediatek.com>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-mediatek@lists.infradead.org>,
        chunhui dai <chunhui.dai@mediatek.com>,
        Bibby Hsieh <bibby.hsieh@mediatek.com>
Date:   Wed, 26 Sep 2018 17:34:29 +0800
In-Reply-To: <67eb0b9c-f2a3-a9c4-202f-d3c64b6a2b3e@gmail.com>
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         <1537925879.20118.3.camel@mtksdaap41>
         <1537929498.32631.16.camel@mtkswgap22>
         <1537939280.20005.19.camel@mtksdaap41>
         <67eb0b9c-f2a3-a9c4-202f-d3c64b6a2b3e@gmail.com>
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On Wed, 2018-09-26 at 10:50 +0200, Matthias Brugger wrote:
> 
> On 26/09/2018 07:21, CK Hu wrote:
> > Hi, Ryder:
> > 
> > On Wed, 2018-09-26 at 10:38 +0800, Ryder Lee wrote:
> >> On Wed, 2018-09-26 at 09:37 +0800, CK Hu wrote:
> >>> Hi, Ryder:
> >>>
> >>> On Wed, 2018-09-05 at 22:09 +0800, Ryder Lee wrote:
> >>>> Add display subsystem related device nodes for MT7623.
> >>>>
> >>>> Cc: CK Hu <ck.hu@mediatek.com>
> >>>> Signed-off-by: chunhui dai <chunhui.dai@mediatek.com>
> >>>> Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
> >>>> Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
> >>>> ---
> >>>> I forgot to sort nodes in my previous mail. Sorry for the inconvenience.
> >>>>
> >>>> This patch depends on the series: https://lkml.org/lkml/2018/9/5/223
> >>>>
> >>>> @Matthias,
> >>>> I know you're working on broken MMSYS - just want to ask whether it's possible
> >>>> to let the patch to go to your tree (if others are okay with it), and send a
> >>>> fixup one for MT7623 MMSYS later?
> >>>> ---
> >>>>  arch/arm/boot/dts/mt7623.dtsi                 | 177 ++++++++++++++++++++++++++
> >>>>  arch/arm/boot/dts/mt7623n-bananapi-bpi-r2.dts |  83 ++++++++++++
> >>>>  arch/arm/boot/dts/mt7623n-rfb-emmc.dts        |  83 ++++++++++++
> >>>>  3 files changed, 343 insertions(+)
> >>>>
> >>>> diff --git a/arch/arm/boot/dts/mt7623.dtsi b/arch/arm/boot/dts/mt7623.dtsi
> >>>> index d01bdee..fdf9078 100644
> >>>> --- a/arch/arm/boot/dts/mt7623.dtsi
> >>>> +++ b/arch/arm/boot/dts/mt7623.dtsi
> >>>> @@ -23,6 +23,11 @@
> >>>>  	#address-cells = <2>;
> >>>>  	#size-cells = <2>;
> >>>>  
> >>>> +	aliases {
> >>>> +		rdma0 = &rdma0;
> >>>> +		rdma1 = &rdma1;
> >>>> +	};
> >>>> +
> >>>>  	cpu_opp_table: opp-table {
> >>>>  		compatible = "operating-points-v2";
> >>>>  		opp-shared;
> >>>> @@ -311,6 +316,25 @@
> >>>>  		clock-names = "spi", "wrap";
> >>>>  	};
> >>>>  
> >>>> +	mipi_tx0: mipi-dphy@10010000 {
> >>>> +		compatible = "mediatek,mt7623-mipi-tx",
> >>>> +			     "mediatek,mt2701-mipi-tx";
> >>>> +		reg = <0 0x10010000 0 0x90>;
> >>>> +		clocks = <&clk26m>;
> >>>> +		clock-output-names = "mipi_tx0_pll";
> >>>> +		#clock-cells = <0>;
> >>>> +		#phy-cells = <0>;
> >>>> +	};
> >>>> +
> >>>> +	cec: cec@10012000 {
> >>>> +		compatible = "mediatek,mt7623-cec",
> >>>> +			     "mediatek,mt8173-cec";
> >>>> +		reg = <0 0x10012000 0 0xbc>;
> >>>> +		interrupts = <GIC_SPI 182 IRQ_TYPE_LEVEL_LOW>;
> >>>> +		clocks = <&infracfg CLK_INFRA_CEC>;
> >>>> +		status = "disabled";
> >>>> +	};
> >>>> +
> >>>>  	cir: cir@10013000 {
> >>>>  		compatible = "mediatek,mt7623-cir";
> >>>>  		reg = <0 0x10013000 0 0x1000>;
> >>>> @@ -359,6 +383,18 @@
> >>>>  		#clock-cells = <1>;
> >>>>  	};
> >>>>  
> >>>> +	hdmi_phy: phy@10209100 {
> >>>> +		compatible = "mediatek,mt7623-hdmi-phy",
> >>>> +			     "mediatek,mt2701-hdmi-phy";
> >>>> +		reg = <0 0x10209100 0 0x24>;
> >>>> +		clocks = <&apmixedsys CLK_APMIXED_HDMI_REF>;
> >>>> +		clock-names = "pll_ref";
> >>>> +		clock-output-names = "hdmitx_dig_cts";
> >>>> +		#clock-cells = <0>;
> >>>> +		#phy-cells = <0>;
> >>>> +		status = "disabled";
> >>>> +	};
> >>>> +
> >>>>  	rng: rng@1020f000 {
> >>>>  		compatible = "mediatek,mt7623-rng";
> >>>>  		reg = <0 0x1020f000 0 0x1000>;
> >>>> @@ -558,6 +594,16 @@
> >>>>  		status = "disabled";
> >>>>  	};
> >>>>  
> >>>> +	hdmiddc0: i2c@11013000 {
> >>>> +		compatible = "mediatek,mt7623-hdmi-ddc",
> >>>> +			     "mediatek,mt8173-hdmi-ddc";
> >>>> +		interrupts = <GIC_SPI 81 IRQ_TYPE_LEVEL_LOW>;
> >>>> +		reg = <0 0x11013000 0 0x1C>;
> >>>> +		clocks = <&pericfg CLK_PERI_I2C3>;
> >>>> +		clock-names = "ddc-i2c";
> >>>> +		status = "disabled";
> >>>> +	};
> >>>> +
> >>>>  	nor_flash: spi@11014000 {
> >>>>  		compatible = "mediatek,mt7623-nor",
> >>>>  			     "mediatek,mt8173-nor";
> >>>> @@ -732,6 +778,84 @@
> >>>>  		#clock-cells = <1>;
> >>>>  	};
> >>>>  
> >>>> +	display_components: dispsys@14000000 {
> >>>> +		compatible = "mediatek,mt7623-mmsys",
> >>>
> >>> Checkpatch warning:
> >>>
> >>> WARNING: DT compatible string "mediatek,mt7623-mmsys" appears
> >>> un-documented -- check ./Documentation/devicetree/bindings/
> >>> #101: FILE: arch/arm/boot/dts/mt7623.dtsi:782:
> >>> +               compatible = "mediatek,mt7623-mmsys",
> >>>
> >>>
> >>>> +			     "mediatek,mt2701-mmsys";
> >>>> +		reg = <0 0x14000000 0 0x1000>;
> >>>> +		power-domains = <&scpsys MT2701_POWER_DOMAIN_DISP>;
> >>>> +	};
> >>>> +
> >>>> +	ovl@14007000 {
> >>>> +		compatible = "mediatek,mt7623-disp-ovl",
> >>>
> >>> I think this is also un-documented, but I don't know why checkpatch does
> >>> not show any warning.
> >>>
> >>> Regards,
> >>> CK
> >>>> +			     "mediatek,mt2701-disp-ovl";
> >>>> +		reg = <0 0x14007000 0 0x1000>;
> >>>> +		interrupts = <GIC_SPI 153 IRQ_TYPE_LEVEL_LOW>;
> >>>> +		clocks = <&mmsys CLK_MM_DISP_OVL>;
> >>>> +		iommus = <&iommu MT2701_M4U_PORT_DISP_OVL_0>;
> >>>> +		mediatek,larb = <&larb0>;
> >>>> +	};
> >>>> +
> >>
> >> I fallback to use the MT2701's compatible string here and there, but I
> >> could add a new one for MT7623.
> >>
> >> BTW, I've had this question for a long time - should I add a new
> >> compatible for the very same IPs, or could we just use the old one in
> >> DTS?
> >>
> >> Ryder
> >>
> > 
> > From [1], there is a description for the multiple compatible string
> > scheme:
> > 
> > ====
> > The reasoning behind this scheme is the observation that in the majority
> > of cases, a single machine_desc can support a large number of boards
> > if they all use the same SoC, or same family of SoCs.  However,
> > invariably there will be some exceptions where a specific board will
> > require special setup code that is not useful in the generic case.
> > Special cases could be handled by explicitly checking for the
> > troublesome board(s) in generic setup code, but doing so very quickly
> > becomes ugly and/or unmaintainable if it is more than just a couple of
> > cases.
> > 
> > Instead, the compatible list allows a generic machine_desc to provide
> > support for a wide common set of boards by specifying "less
> > compatible" values in the dt_compat list.  In the example above,
> > generic board support can claim compatibility with "ti,omap3" or
> > "ti,omap3450".  If a bug was discovered on the original beagleboard
> > that required special workaround code during early boot, then a new
> > machine_desc could be added which implements the workarounds and only
> > matches on "ti,omap3-beagleboard".
> > ====
> > 
> > I don't know would there be a problem happened only in MT7623 even
> > though this hardware is identical in both MT2701 and MT7623. Maybe the
> > system-wide configuration would influence this driver. So the easy way
> > is to add the compatible string for MT7623. If you could prove that 
> > this driver would never be influenced by system-wide configuration,
> > using only MT2701 compatible string is acceptable for me.
> > 
> > This is my opinion, but the most important is maintainer's opinion.
> > 
> 
> The compatible string looks good. But you should update the binding documentation :)

Okay, I will update it.

> Regards,
> Matthias