linux-kernel - Re: [RFC v3 5/7] phy: qcom: phy-qcom-snps-eusb2: Add support for eUSB2 repeater

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Message-ID: <Y+H5hxaOeGTP+wrt@linaro.org>
Date:   Tue, 7 Feb 2023 09:11:03 +0200
From:   Abel Vesa <abel.vesa@...aro.org>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Lee Jones <lee@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-phy@...ts.infradead.org,
        Neil Armstrong <neil.armstrong@...aro.org>
Subject: Re: [RFC v3 5/7] phy: qcom: phy-qcom-snps-eusb2: Add support for
 eUSB2 repeater

On 23-02-03 19:19:22, Vinod Koul wrote:
> On 02-02-23, 15:38, Abel Vesa wrote:
> > From: Neil Armstrong <neil.armstrong@...aro.org>
> > 
> > For USB 2.0 compliance, eUSB2 needs a repeater. The PHY needs to
> > initialize and reset it. So add repeater support
> > 
> > Co-developed-by: Abel Vesa <abel.vesa@...aro.org>
> > Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
> > Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
> > ---
> >  drivers/phy/qualcomm/phy-qcom-snps-eusb2.c | 18 +++++++++++++++++-
> >  1 file changed, 17 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/phy/qualcomm/phy-qcom-snps-eusb2.c b/drivers/phy/qualcomm/phy-qcom-snps-eusb2.c
> > index 23ec162cc3bd..8d972d49732b 100644
> > --- a/drivers/phy/qualcomm/phy-qcom-snps-eusb2.c
> > +++ b/drivers/phy/qualcomm/phy-qcom-snps-eusb2.c
> > @@ -128,6 +128,8 @@ struct qcom_snps_eusb2_hsphy {
> >  	struct regulator_bulk_data vregs[EUSB2_NUM_VREGS];
> >  
> >  	enum phy_mode mode;
> > +
> > +	struct phy *repeater;
> >  };
> >  
> >  static int qcom_snps_eusb2_hsphy_set_mode(struct phy *p, enum phy_mode mode, int submode)
> > @@ -136,7 +138,7 @@ static int qcom_snps_eusb2_hsphy_set_mode(struct phy *p, enum phy_mode mode, int
> >  
> >  	phy->mode = mode;
> >  
> > -	return 0;
> > +	return phy_set_mode_ext(phy->repeater, mode, submode);
> >  }
> >  
> >  static void qcom_snps_eusb2_hsphy_write_mask(void __iomem *base, u32 offset,
> > @@ -235,6 +237,12 @@ static int qcom_snps_eusb2_hsphy_init(struct phy *p)
> >  	if (ret)
> >  		return ret;
> >  
> > +	ret = phy_init(phy->repeater);
> > +	if (ret) {
> > +		dev_err(&p->dev, "repeater init failed. %d\n", ret);
> > +		goto disable_vreg;
> > +	}
> > +
> >  	ret = clk_prepare_enable(phy->ref_clk);
> >  	if (ret) {
> >  		dev_err(&p->dev, "failed to enable ref clock, %d\n", ret);
> > @@ -342,6 +350,8 @@ static int qcom_snps_eusb2_hsphy_exit(struct phy *p)
> >  
> >  	regulator_bulk_disable(ARRAY_SIZE(phy->vregs), phy->vregs);
> >  
> > +	phy_exit(phy->repeater);
> > +
> >  	return 0;
> >  }
> >  
> > @@ -386,6 +396,12 @@ static int qcom_snps_eusb2_hsphy_probe(struct platform_device *pdev)
> >  	if (ret)
> >  		return dev_err_probe(dev, ret,
> >  				     "failed to get regulator supplies\n");
> > +
> > +	phy->repeater = devm_phy_get(dev, "eusb2-repeater");
> > +	if (IS_ERR(phy->repeater))
> > +		return dev_err_probe(dev, PTR_ERR(phy->repeater),
> > +				     "failed to get repeater\n");
> 
> That implies repeater is assumed to be there for all designs, how about
> older devices, they may not have a repeater?

Well, no other (older) platform has eUSB2 support, IIRC.

And the eUSB2 can't be used as USB 2.0 without the repeater.

> 
> > +
> >  	generic_phy = devm_phy_create(dev, NULL, &qcom_snps_eusb2_hsphy_ops);
> >  	if (IS_ERR(generic_phy)) {
> >  		dev_err(dev, "failed to create phy %d\n", ret);
> > -- 
> > 2.34.1
> 
> -- 
> ~Vinod