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Date:   Tue, 13 Nov 2018 11:42:08 +0800
From:   Shawn Guo <shawn.guo@linaro.org>
To:     Rob Herring <robh@kernel.org>
Cc:     Kishon Vijay Abraham I <kishon@ti.com>,
        Sriharsha Allenki <sallenki@codeaurora.org>,
        Anu Ramanathan <anur@codeaurora.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Vinod Koul <vkoul@kernel.org>, linux-arm-msm@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: phy: Add Qualcomm Synopsys High-Speed
 USB PHY binding
Message-ID: <20181113034200.GD20049@tiger>
References: <20181108070449.23572-1-shawn.guo@linaro.org>
 <20181108070449.23572-2-shawn.guo@linaro.org>
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Hi Rob,

On Mon, Nov 12, 2018 at 01:24:51PM -0600, Rob Herring wrote:
> On Thu, Nov 08, 2018 at 03:04:48PM +0800, Shawn Guo wrote:
> > From: Sriharsha Allenki <sallenki@codeaurora.org>
> > 
> > It adds bindings for Synopsys 28nm femto phy controller that supports
> > LS/FS/HS usb connectivity on Qualcomm chipsets.
> > 
> > Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>
> > Signed-off-by: Anu Ramanathan <anur@codeaurora.org>
> > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> > Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> > ---
> >  .../phy/qcom,snps-28nm-usb-hs-phy.txt         | 101 ++++++++++++++++++
> >  1 file changed, 101 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/phy/qcom,snps-28nm-usb-hs-phy.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/phy/qcom,snps-28nm-usb-hs-phy.txt b/Documentation/devicetree/bindings/phy/qcom,snps-28nm-usb-hs-phy.txt
> > new file mode 100644
> > index 000000000000..75e7a09dd558
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/phy/qcom,snps-28nm-usb-hs-phy.txt
> > @@ -0,0 +1,101 @@
> > +Qualcomm Synopsys 28nm Femto phy controller
> > +===========================================
> > +
> > +Synopsys 28nm femto phy controller supports LS/FS/HS usb connectivity on
> > +Qualcomm chipsets.
> > +
> > +Required properties:
> > +
> > +- compatible:
> > +    Value type: <string>
> > +    Definition: Should contain "qcom,usb-snps-hsphy".
> 
> SoC specific compatible?

Agreed.  A SoC prefixed compatible would be more specific and scalable
for handling different programming model of the same IP.  I will use
"qcom,qcs404-usb-hsphy" in v3.

> 
> > +
> > +- reg:
> > +    Value type: <prop-encoded-array>
> > +    Definition: USB PHY base address and length of the register map.
> > +
> > +- #phy-cells:
> > +    Value type: <u32>
> > +    Definition: Should be 0.
> > +
> > +- clocks:
> > +    Value type: <prop-encoded-array>
> > +    Definition: See clock-bindings.txt section "consumers". List of
> > +		three clock specifiers for reference, phy core and
> > +		sleep clocks.
> > +
> > +- clock-names:
> > +    Value type: <string>
> > +    Definition: Names of the clocks in 1-1 correspondence with the "clocks"
> > +		property. Must contain "ref", "phy" and "sleep".
> > +
> > +- resets:
> > +    Value type: <prop-encoded-array>
> > +    Definition: See reset.txt section "consumers". PHY reset specifiers
> > +		for phy core and POR resets.
> > +
> > +- reset-names:
> > +    Value type: <string>
> > +    Definition: Names of the resets in 1-1 correspondence with the "resets"
> > +		property. Must contain "phy" and "por".
> > +
> > +- vdd-supply:
> > +    Value type: <phandle>
> > +    Definition: phandle to the regulator VDD supply node.
> > +
> > +- vdda1p8-supply:
> > +    Value type: <phandle>
> > +    Definition: phandle to the regulator 1.8V supply node.
> > +
> > +- vdda3p3-supply:
> > +    Value type: <phandle>
> > +    Definition: phandle to the regulator 3.3V supply node.
> > +
> > +- qcom,vdd-voltage-level:
> > +    Value type: <prop-array>
> > +    Definition: This is a list of three integer values <no min max> where
> > +		each value corresponding to voltage corner in uV.
> > +
> > +Optional properties:
> > +
> > +- extcon:
> > +    Value type: <prop-encoded-array>
> > +    Definition: Should contain the vbus extcon.
> 
> Don't use extcon for new bindings. Use usb-connector binding.

Okay, I just did a bit of research and found that 'extcon' is becoming
a deprecated DT property recently and we should OF graph bindings to
specify the connector.  Will do in v3.

> 
> > +
> > +- qcom,init-seq:
> > +    Value type: <u32 array>
> > +    Definition: Should contain a sequence of <offset value delay> tuples to
> > +                program 'value' into phy register at 'offset' with 'delay'
> > +		in us afterwards.
> 
> If we wanted this type of thing in DT, we'd have a generic binding (or 
> forth).

Right now, this is a qualcomm usb phy specific bindings - first used in
qcom,usb-hs-phy.txt and I extended it a bit for my phy.  As this is not
a so good hardware description, I'm a little hesitated to make it
generic for other platforms to use in general.  What about we put off it
a little bit until we see more platforms need the same thing?

Shawn

> This should probably be split between SoC specific settings in 
> the driver and board properties in DT.