linux-kernel - Re: [RFC PATCH v2 1/3] dt-bindings: phy: qcom,qmp-usb3-dp: Add sm6350 compatible

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Date:   Fri, 25 Nov 2022 13:53:25 +0100
From:   "Luca Weiss" <luca.weiss@...rphone.com>
To:     "Johan Hovold" <johan@...nel.org>
Cc:     <linux-arm-msm@...r.kernel.org>,
        <~postmarketos/upstreaming@...ts.sr.ht>,
        <phone-devel@...r.kernel.org>, "Andy Gross" <agross@...nel.org>,
        "Bjorn Andersson" <andersson@...nel.org>,
        "Konrad Dybcio" <konrad.dybcio@...aro.org>,
        "Vinod Koul" <vkoul@...nel.org>,
        "Kishon Vijay Abraham I" <kishon@...nel.org>,
        "Rob Herring" <robh+dt@...nel.org>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@...aro.org>,
        <linux-phy@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v2 1/3] dt-bindings: phy: qcom,qmp-usb3-dp: Add
 sm6350 compatible

On Fri Nov 25, 2022 at 11:19 AM CET, Johan Hovold wrote:
> On Fri, Nov 25, 2022 at 10:55:31AM +0100, Luca Weiss wrote:
> > Hi Johan,
> > 
> > On Fri Nov 25, 2022 at 10:50 AM CET, Johan Hovold wrote:
> > > On Fri, Nov 25, 2022 at 10:27:47AM +0100, Luca Weiss wrote:
> > > > Add the compatible describing the combo phy found on SM6350.
> > > > 
> > > > Signed-off-by: Luca Weiss <luca.weiss@...rphone.com>
> > > > ---
> > > > @Johan Hovold, I've sent this v2 as RFC because there are several things
> > > > where I have questions on how it should be done.
> > > > 
> > > > In this patch, you can see there's cfg_ahb (&xo_board) and power-domains
> > > > is not set. In msm-4.19 &gcc_usb30_prim_gdsc is only used in the
> > > > ssusb@...0000 node, or should I also add it to qmpphy?
> > >
> > > Yeah, you may need to add a platform specific section of the clocks,
> > > which appear to be different, even if I'm not sure they are currently
> > > described correctly (xo_board as cfg_ahb and "QLINK" as ref). How are
> > > they named in the vendor's dts?
> > 
> > This is the msm-4.19 dts:
> > https://android.googlesource.com/kernel/msm-extra/devicetree/+/refs/heads/android-msm-bramble-4.19-android11-qpr1/qcom/lagoon-usb.dtsi#354
>
> 		clocks = <&gcc GCC_USB3_PRIM_PHY_AUX_CLK>,
> 			<&gcc GCC_USB3_PRIM_PHY_PIPE_CLK>,
> 			<&rpmhcc RPMH_QLINK_CLK>,
> 			<&gcc GCC_USB3_PRIM_CLKREF_CLK>,
> 			<&gcc GCC_USB3_PRIM_PHY_COM_AUX_CLK>;
> 		clock-names = "aux_clk", "pipe_clk", "ref_clk_src",
> 				"ref_clk", "com_aux_clk";
>
> So it looks like you don't need update the binding for the clocks as the
> above matches sc8280xp:
>
> 	aux
> 	ref
> 	com_aux
> 	usb3_pipe

Thanks for checking!

>
> Parent clocks (ref_clk_src) should not be included in the binding, but
> rather be handled by the clock driver. For example, see:
>
> 	https://lore.kernel.org/all/20221121085058.31213-4-johan+linaro@kernel.org/
> 	https://lore.kernel.org/all/20221115152956.21677-1-quic_shazhuss@quicinc.com/

So I assume you mean that I shouldn't do this:

clocks = <&gcc GCC_USB3_PRIM_PHY_AUX_CLK>,
     <&rpmhcc RPMH_QLINK_CLK>,
     <&gcc GCC_USB3_PRIM_PHY_COM_AUX_CLK>,
     <&gcc GCC_USB3_PRIM_PHY_PIPE_CLK>;
clock-names = "aux", "ref", "com_aux", "usb3_pipe";

But for "ref" use GCC_USB3_PRIM_CLKREF_CLK? That also seems to work
fine, also if RPMH_QLINK_CLK is not used from Linux-side (checked in
debugfs).


And for the driver patch, I've discovered that this phy doesn't have
separate txa/tbx region, so dts was also wrong there. Do you know if
there's a way to test DP phy initialization without having all the USB-C
plumbing in place? Might be good to validate at least phy init works if
we're already touching all of this.

Regards
Luca

>
> > > >  .../bindings/phy/qcom,sc8280xp-qmp-usb43dp-phy.yaml          | 5 +++--
> > > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-usb43dp-phy.yaml b/Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-usb43dp-phy.yaml
> > > > index 6f31693d9868..3e39e3e0504d 100644
> > > > --- a/Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-usb43dp-phy.yaml
> > > > +++ b/Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-usb43dp-phy.yaml
> > > > @@ -17,16 +17,18 @@ properties:
> > > >    compatible:
> > > >      enum:
> > > >        - qcom,sc8280xp-qmp-usb43dp-phy
> > > > +      - qcom,sm6350-qmp-usb3-dp-phy
> > > >  
> > > >    reg:
> > > >      maxItems: 1
> > > >  
> > > >    clocks:
> > > > -    maxItems: 4
> > > > +    maxItems: 5
> > > >  
> > > >    clock-names:
> > > >      items:
> > > >        - const: aux
> > > > +      - const: cfg_ahb
> > > >        - const: ref
> > > >        - const: com_aux
> > > >        - const: usb3_pipe
> > >
> > > So this would need to be moved to an allOf: construct at the end with
> > > one section each for sc8280xp and sm6350.
> > 
> > Ack.
>
> So no need to change this it seems.
>
> Johan