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Date: Mon, 25 Dec 2023 18:11:24 +0800
From: fuyao <fuyao@sjterm.com>
To: Andre Przywara <andre.przywara@arm.com>
Cc: fuyao <fuyao1697@cyg.com>, Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Samuel Holland <samuel@sholland.org>,
	Alexandre TORGUE <alexandre.torgue@st.com>,
	Enric Balletbo i Serra <eballetbo@gmail.com>,
	Baruch Siach <baruch@tkos.co.il>,
	Paul Barker <paul.barker@sancloud.com>, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH RESEND] ARM: dts: sun8i: r40: open the regulator aldo1
Message-ID: <ZYlVTFrWkPaci92K@debian.cyg>
Mail-Followup-To: Andre Przywara <andre.przywara@arm.com>,
	fuyao <fuyao1697@cyg.com>, Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Samuel Holland <samuel@sholland.org>,
	Alexandre TORGUE <alexandre.torgue@st.com>,
	Enric Balletbo i Serra <eballetbo@gmail.com>,
	Baruch Siach <baruch@tkos.co.il>,
	Paul Barker <paul.barker@sancloud.com>, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev,
	linux-kernel@vger.kernel.org
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 <20231220150400.0f32e2a5@donnerap.manchester.arm.com>
 <ZYOhAQi7XeLUuAC9@debian.cyg>
 <20231221103906.1830ef94@donnerap.manchester.arm.com>
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Organization: work_work_work

On Thu, Dec 21, 2023 at 10:39:06AM +0000, Andre Przywara wrote:
> On Thu, 21 Dec 2023 10:20:49 +0800
> fuyao <fuyao@sjterm.com> wrote:
> 
> Hi,
> 
> thanks for the reply!
> 
> > On Wed, Dec 20, 2023 at 03:04:00PM +0000, Andre Przywara wrote:
> > > On Wed, 20 Dec 2023 16:18:43 +0800
> > > fuyao <fuyao1697@cyg.com> wrote:
> > > 
> > > Hi,
> > >   
> > > > the aldo1 is connect regulator pin which power the TV.  
> > > 
> > > What do you mean with that? That ALDO1 is connected to VCC-TVOUT and/or
> > > VCC-TVIN on the R40 SoC?  
> > 
> > The ALDO1 is connected to VCC-TVOUT on the R40 Soc.
> 
> Ah, thanks for the confirmation.
> 
> > > > The USB core use TV ref as reference Voltage.  
> > > 
> > > The USB core in the SoC? So pin VCC-USB, which requires 3.3V, the same
> > > voltage as the TV pins?
> > > Which means this doesn't really have much to do with TV, it's just that
> > > USB and also "TV" are supplied by ALDO1?  
> > 
> > The internal USB PHY requires a reference voltage. It seems that in
> > order to save costs, the reference voltage of the TVOUT module is used.
> 
> Do you mean a USB *reference* voltage that is separate from the USB PHY
> power supply voltage, so pin VCC-USB on the SoC? And that it is internally
> connected to some TV-OUT related circuits? So that would apply to all
> devices using the R40 SoC then?
yes, The usb need a power from TV module insides.
> 
> Or is it simply that the SoC pins VCC-TVOUT and VCC-USB are connected
> together, on this SoM?
no
> Do you have access to some schematic? I couldn't find one online easily,
> so cannot check this myself.
> 
It has up to https://file.io/VSUL4FDrapDY
> Thanks,
> Andre
> 
> > > > Signed-off-by: fuyao <fuyao1697@cyg.com>
> > > > ---
> > > >  arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi | 7 +++++++
> > > >  1 file changed, 7 insertions(+)
> > > > 
> > > > diff --git a/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi b/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi
> > > > index 9f39b5a2bb35..8906170461df 100644
> > > > --- a/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi
> > > > +++ b/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi
> > > > @@ -42,6 +42,13 @@ &pio {
> > > >  	vcc-pg-supply = <&reg_dldo1>;
> > > >  };
> > > >  
> > > > +&reg_aldo1 {
> > > > +	regulator-always-on;  
> > > 
> > > So did USB never work before, with the DT as in mainline?
> > >   
> > 
> > The USB can work, but is unstable. Occasionally disconnected because of
> > the D+/D- electrical characteristics.
> > 
> > > For always-on regulators it would be good to see some rationale why this
> > > cannot be referenced by its consumer. If it is really supplying the USB
> > > core, that would be a reason, because we don't have a good way of
> > > describing this.
> > >   
> > > > +	regulator-min-microvolt = <3300000>;
> > > > +	regulator-max-microvolt = <3300000>;
> > > > +	regulator-name = "vcc-aldo1";  
> > > 
> > > Regulators should be named after their users, so use something like:
> > > 	regulator-name = "vcc-3v3-tv-usb";
> > >   
> > 
> > thanks.
> > 
> > > That then also serves as documentation of why this is always on.
> > > 
> > > Cheers,
> > > Andre
> > >   
> > > > +};
> > > > +
> > > >  &reg_aldo2 {
> > > >  	regulator-always-on;
> > > >  	regulator-min-microvolt = <1800000>;  
> > >   
> > 

-- 
fuyao [付尧]