linux-kernel - [PATCH v5 10/14] phy: qcom: qmp-usbc: Add USB/DP exclude handling

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Message-Id: <20250919-add-displayport-support-for-qcs615-platform-v5-10-eae6681f4002@oss.qualcomm.com>
Date: Fri, 19 Sep 2025 22:24:27 +0800
From: Xiangxu Yin <xiangxu.yin@....qualcomm.com>
To: 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>,
        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>
Cc: 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,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Xiangxu Yin <xiangxu.yin@....qualcomm.com>
Subject: [PATCH v5 10/14] phy: qcom: qmp-usbc: Add USB/DP exclude handling

When both USB and DP PHY modes are enabled simultaneously on the same
QMP USBC PHY, it can lead to hardware misconfiguration and undefined
behavior. This happens because the PHY resources are not designed to
operate in both modes at the same time.

To prevent this, introduce a mutual exclusion check between USB and DP
PHY modes.

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 74dcf954845bcf8209202b75e9db10c3f6bdebd9..8030422d64382aa231d69dec9788778cdb0f218e 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c
@@ -670,6 +670,19 @@ static int qmp_usbc_usb_power_off(struct phy *phy)
 	return 0;
 }
 
+static int qmp_usbc_check_phy_status(struct qmp_usbc *qmp, bool is_dp)
+{
+	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);
@@ -677,6 +690,10 @@ static int qmp_usbc_usb_enable(struct phy *phy)
 
 	mutex_lock(&qmp->phy_mutex);
 
+	ret = qmp_usbc_check_phy_status(qmp, false);
+	if (ret)
+		goto out_unlock;
+
 	ret = qmp_usbc_com_init(phy);
 	if (ret)
 		goto out_unlock;
@@ -730,6 +747,10 @@ static int qmp_usbc_dp_enable(struct phy *phy)
 
 	mutex_lock(&qmp->phy_mutex);
 
+	ret = qmp_usbc_check_phy_status(qmp, true);
+	if (ret)
+		goto dp_init_unlock;
+
 	ret = qmp_usbc_com_init(phy);
 	if (ret)
 		goto dp_init_unlock;

-- 
2.34.1