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

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Message-ID: <f030649a-9505-4bda-9ce9-00eeee8d3b06@oss.qualcomm.com>
Date: Mon, 15 Sep 2025 18:12:10 +0800
From: Xiangxu Yin <xiangxu.yin@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....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 9/12/2025 8:09 PM, Dmitry Baryshkov wrote:
> 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()?


Ok.


>>
>>>> +{
>>>> +	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);