linux-kernel - [PATCH v3 31/38] drm/msm/dp: add HPD callback for dp MST

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Message-Id: <20250825-msm-dp-mst-v3-31-01faacfcdedd@oss.qualcomm.com>
Date: Mon, 25 Aug 2025 22:16:17 +0800
From: Yongxing Mou <yongxing.mou@....qualcomm.com>
To: 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, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Yongxing Mou <yongxing.mou@....qualcomm.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>
Subject: [PATCH v3 31/38] drm/msm/dp: add HPD callback for dp MST

From: Abhinav Kumar <quic_abhinavk@...cinc.com>

Add HPD callback for the MST module which shall be invoked from the
dp_display's HPD handler to perform MST specific operations in case
of HPD. In MST case, route the HPD messages to MST module.

Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
Signed-off-by: Yongxing Mou <yongxing.mou@....qualcomm.com>
---
 drivers/gpu/drm/msm/dp/dp_display.c | 15 ++++++++++++---
 drivers/gpu/drm/msm/dp/dp_mst_drm.c | 34 ++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/msm/dp/dp_mst_drm.h |  2 ++
 3 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index abcab3ed43b6da5ef898355cf9b7561cd9fe0404..59720e1ad4b1193e33a4fc6aad0c401eaf9cbec8 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -500,9 +500,16 @@ static int msm_dp_display_handle_irq_hpd(struct msm_dp_display_private *dp)
 
 static int msm_dp_display_usbpd_attention_cb(struct device *dev)
 {
-	int rc = 0;
-	u32 sink_request;
 	struct msm_dp_display_private *dp = dev_get_dp_display_private(dev);
+	struct msm_dp *msm_dp_display = &dp->msm_dp_display;
+	u32 sink_request;
+	int rc = 0;
+
+	if (msm_dp_display->mst_active) {
+		if (msm_dp_aux_is_link_connected(dp->aux) != ISR_DISCONNECTED)
+			msm_dp_mst_display_hpd_irq(&dp->msm_dp_display);
+		return 0;
+	}
 
 	/* check for any test request issued by sink */
 	rc = msm_dp_link_process_request(dp->link);
@@ -1129,8 +1136,10 @@ static irqreturn_t msm_dp_display_irq_thread(int irq, void *dev_id)
 	if (hpd_isr_status & DP_DP_HPD_UNPLUG_INT_MASK)
 		msm_dp_display_send_hpd_notification(dp, false);
 
-	if (hpd_isr_status & DP_DP_IRQ_HPD_INT_MASK)
+	if (hpd_isr_status & DP_DP_IRQ_HPD_INT_MASK) {
 		msm_dp_display_send_hpd_notification(dp, true);
+		msm_dp_irq_hpd_handle(dp, 0);
+	}
 
 	ret = IRQ_HANDLED;
 
diff --git a/drivers/gpu/drm/msm/dp/dp_mst_drm.c b/drivers/gpu/drm/msm/dp/dp_mst_drm.c
index b4f640134af544c77ab262d2cbe0b67e1e2e1b3a..331d08854049d9c74d49aa231f3507539986099e 100644
--- a/drivers/gpu/drm/msm/dp/dp_mst_drm.c
+++ b/drivers/gpu/drm/msm/dp/dp_mst_drm.c
@@ -567,6 +567,40 @@ static struct msm_dp_mst_bridge_state *msm_dp_mst_br_priv_state(struct drm_atomi
 	return to_msm_dp_mst_bridge_state_priv(obj_state);
 }
 
+/* DP MST HPD IRQ callback */
+void msm_dp_mst_display_hpd_irq(struct msm_dp *dp_display)
+{
+	int rc;
+	struct msm_dp_mst *mst = dp_display->msm_dp_mst;
+	u8 ack[8] = {};
+	u8 esi[4];
+	unsigned int esi_res = DP_SINK_COUNT_ESI + 1;
+	bool handled;
+
+	rc = drm_dp_dpcd_read(mst->dp_aux, DP_SINK_COUNT_ESI,
+			      esi, 4);
+	if (rc != 4) {
+		DRM_ERROR("dpcd sink status read failed, rlen=%d\n", rc);
+		return;
+	}
+
+	drm_dbg_dp(dp_display->drm_dev, "mst irq: esi1[0x%x] esi2[0x%x] esi3[%x]\n",
+		   esi[1], esi[2], esi[3]);
+
+	rc = drm_dp_mst_hpd_irq_handle_event(&mst->mst_mgr, esi, ack, &handled);
+
+	/* ack the request */
+	if (handled) {
+		rc = drm_dp_dpcd_writeb(mst->dp_aux, esi_res, ack[1]);
+
+		if (rc != 1)
+			DRM_ERROR("dpcd esi_res failed. rc=%d\n", rc);
+
+		drm_dp_mst_hpd_irq_send_new_request(&mst->mst_mgr);
+	}
+	drm_dbg_dp(dp_display->drm_dev, "mst display hpd_irq handled:%d rc:%d\n", handled, rc);
+}
+
 /* DP MST Connector OPs */
 static int
 msm_dp_mst_connector_detect(struct drm_connector *connector,
diff --git a/drivers/gpu/drm/msm/dp/dp_mst_drm.h b/drivers/gpu/drm/msm/dp/dp_mst_drm.h
index 1484fabd92ad0075eac5369aac8ca462acbd3eda..5e1b4db8aea4506b0e1cc1cc68980dd617d3f72a 100644
--- a/drivers/gpu/drm/msm/dp/dp_mst_drm.h
+++ b/drivers/gpu/drm/msm/dp/dp_mst_drm.h
@@ -86,4 +86,6 @@ int msm_dp_mst_drm_bridge_init(struct msm_dp *dp, struct drm_encoder *encoder);
 
 int msm_dp_mst_init(struct msm_dp *dp_display, u32 max_streams, struct drm_dp_aux *drm_aux);
 
+void msm_dp_mst_display_hpd_irq(struct msm_dp *dp_display);
+
 #endif /* _DP_MST_DRM_H_ */

-- 
2.34.1