linux-kernel - Re: [PATCH v4 08/13] phy: qcom: qmp-usbc: Add USB/DP switchable PHY clk register

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Message-ID: <ykxl2xjrabsvs6llaf6p3cpiler2nhyrsbnhrbvhtl2is27cig@fbtj45n4e2yd>
Date: Mon, 15 Sep 2025 13:14:12 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Xiangxu Yin <xiangxu.yin@....qualcomm.com>
Cc: Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Rob Clark <robin.clark@....qualcomm.com>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jessica.zhang@....qualcomm.com>,
        Sean Paul <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        fange.zhang@....qualcomm.com, yongxing.mou@....qualcomm.com,
        li.liu@....qualcomm.com, tingwei.zhang@....qualcomm.com,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>
Subject: Re: [PATCH v4 08/13] phy: qcom: qmp-usbc: Add USB/DP switchable PHY
 clk register

On Mon, Sep 15, 2025 at 06:02:19PM +0800, Xiangxu Yin wrote:
> 
> On 9/12/2025 8:08 PM, Dmitry Baryshkov wrote:
> > On Fri, Sep 12, 2025 at 08:00:14PM +0800, Xiangxu Yin wrote:
> >> On 9/12/2025 6:19 PM, Dmitry Baryshkov wrote:
> >>> On Thu, Sep 11, 2025 at 10:55:05PM +0800, Xiangxu Yin wrote:
> >>>> Add USB/DP switchable PHY clock registration and DT parsing for DP offsets.
> >>>> Extend qmp_usbc_register_clocks and clock provider logic to support both
> >>>> USB and DP instances.
> >>>>
> >>>> Signed-off-by: Xiangxu Yin <xiangxu.yin@....qualcomm.com>
> >>>> ---
> >>>>  drivers/phy/qualcomm/phy-qcom-qmp-usbc.c | 208 +++++++++++++++++++++++++++++--
> >>>>  1 file changed, 195 insertions(+), 13 deletions(-)

> >>>> +	default:
> >>>> +		return 0;
> >>>> +	}
> >>>> +}
> >>>> +
> >>>> +static int qmp_usbc_register_clocks(struct qmp_usbc *qmp, struct device_node *np)
> >>>> +{
> >>>> +	int ret;
> >>>>  
> >>>> -	ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &fixed->hw);
> >>>> +	ret = phy_pipe_clk_register(qmp, np);
> >>>>  	if (ret)
> >>>>  		return ret;
> >>>>  
> >>>> -	/*
> >>>> -	 * Roll a devm action because the clock provider is the child node, but
> >>>> -	 * the child node is not actually a device.
> >>>> -	 */
> >>>> -	return devm_add_action_or_reset(qmp->dev, phy_clk_release_provider, np);
> >>>> +	if (qmp->dp_serdes != 0) {
> >>>> +		ret = phy_dp_clks_register(qmp, np);
> >>>> +		if (ret)
> >>>> +			return ret;
> >>>> +	}
> >>>> +
> >>>> +	return devm_of_clk_add_hw_provider(qmp->dev, qmp_usbc_clks_hw_get, qmp);
> >>> Do you understand what did the comment (that you've removed) say? And
> >>> why?
> >
> > And this was ignored :-(
> 
> Sorry for missing this part.
> 
> For USB-C PHY, the legacy implementation only supports USB with a single
> device node. The new driver for USB and DP also uses a single device node.

There is no 'new driver'. It's about DT.

> The function devm_of_clk_add_hw_provider internally handles both
> of_clk_add_hw_provider and devres_add, and supports automatic resource
> release.
> 
> So I think using devm_of_clk_add_hw_provider allows us to remove
> of_clk_add_hw_provider and devm_add_action_or_reset.

Which node is passed to of_clk_add_hw_provider() in the legacy DT case?
Which node is passed to of_clk_add_hw_provider() by
devm_of_clk_add_hw_provider()?

> For combo PHY, the legacy implementation uses two device nodes: dp_np and
> usb_np. To maintain forward compatibility, we need to keep support for
> both nodes and retain the related logic.

-- 
With best wishes
Dmitry