linux-kernel - Re: [PATCH v4 11/13] phy: qcom: qmp-usbc: Add USB/DP mutex handling

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Message-ID: <q4dplt6fq3cneludcuhxevklaj6omeio3cjxw2owt4h3wistd6@arv23ri4cl75>
Date: Fri, 12 Sep 2025 15:09:17 +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 11/13] phy: qcom: qmp-usbc: Add USB/DP mutex handling

On Fri, Sep 12, 2025 at 08:03:01PM +0800, Xiangxu Yin wrote:
> 
> On 9/12/2025 6:32 PM, Dmitry Baryshkov wrote:
> > On Thu, Sep 11, 2025 at 10:55:08PM +0800, Xiangxu Yin wrote:
> >> Introduce mutual exclusion between USB and DP PHY modes to prevent
> >> simultaneous activation.
> > Describe the problem that you are trying to solve first.
> 
> 
> Ok.
> 
> 
> >> Signed-off-by: Xiangxu Yin <xiangxu.yin@....qualcomm.com>
> >> ---
> >>  drivers/phy/qualcomm/phy-qcom-qmp-usbc.c | 21 +++++++++++++++++++++
> >>  1 file changed, 21 insertions(+)
> >>
> >> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c b/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c
> >> index 613239d15a6a3bba47a647db4e663713f127c93e..866277036089c588cf0c63204efb91bbec5430ae 100644
> >> --- a/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c
> >> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c
> >> @@ -1061,6 +1061,19 @@ static int qmp_usbc_usb_power_off(struct phy *phy)
> >>  	return 0;
> >>  }
> >>  
> >> +static int qmp_check_mutex_phy(struct qmp_usbc *qmp, bool is_dp)
> > mutex has a very well defined use case - a sleeping lock. Please find
> > some ofther name.
> 
> 
> Then how about 'qmp_check_exclude_phy'?


qmp_usbc_check_phy_status()?

> 
> 
> >> +{
> >> +	if ((is_dp && qmp->usb_init_count) ||
> >> +	    (!is_dp && qmp->dp_init_count)) {
> >> +		dev_err(qmp->dev,
> >> +			"PHY is configured for %s, can not enable %s\n",
> >> +			is_dp ? "USB" : "DP", is_dp ? "DP" : "USB");
> >> +		return -EBUSY;
> >> +	}
> >> +
> >> +	return 0;
> >> +}
> >> +
> >>  static int qmp_usbc_usb_enable(struct phy *phy)
> >>  {
> >>  	struct qmp_usbc *qmp = phy_get_drvdata(phy);

-- 
With best wishes
Dmitry