[PATCH v4 37/39] drm/msm/dp: add HPD callback for dp MST

Yongxing Mou
2026-04-10T09:37:04Z

From: Abhinav Kumar <quic_abhinavk@quicinc.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@quicinc.com>
Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
---
drivers/gpu/drm/msm/dp/dp_display.c | 23 +++++++++++++++++++----
drivers/gpu/drm/msm/dp/dp_mst_drm.c | 34 ++++++++++++++++++++++++++++++++++
drivers/gpu/drm/msm/dp/dp_mst_drm.h | 1 +
3 files changed, 54 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 919767945ba5..ca89e20b7563 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -454,6 +454,9 @@ static int msm_dp_hpd_plug_handle(struct msm_dp_display_private *dp)
dp->msm_dp_display.connector_type,
dp->link->sink_count);

+ if (dp->plugged)
+ return 0;
+
mutex_lock(&dp->plugged_lock);

ret = pm_runtime_resume_and_get(&pdev->dev);
@@ -556,12 +559,19 @@ static int msm_dp_irq_hpd_handle(struct msm_dp_display_private *dp)
{
u32 sink_request;
int rc = 0;
+ struct msm_dp *msm_dp_display = &dp->msm_dp_display;

/* irq_hpd can happen at either connected or disconnected state */
drm_dbg_dp(dp->drm_dev, "Before, type=%d, sink_count=%d\n",
dp->msm_dp_display.connector_type,
dp->link->sink_count);

+ 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);
if (!rc) {
@@ -1125,9 +1135,13 @@ static irqreturn_t msm_dp_display_irq_thread(int irq, void *dev_id)
connector_status_connected);

/* Send HPD as connected and distinguish it in the notifier */
- if (hpd_isr_status & DP_DP_IRQ_HPD_INT_MASK)
- drm_bridge_hpd_notify(dp->msm_dp_display.bridge,
- connector_status_connected);
+ if (hpd_isr_status & DP_DP_IRQ_HPD_INT_MASK) {
+ if (dp->msm_dp_display.mst_active)
+ msm_dp_irq_hpd_handle(dp);
+ else
+ drm_bridge_hpd_notify(dp->msm_dp_display.bridge,
+ connector_status_connected);
+ }

ret = IRQ_HANDLED;

@@ -1793,7 +1807,8 @@ void msm_dp_bridge_hpd_notify(struct drm_bridge *bridge,
msm_dp_hpd_plug_handle(dp);
}
} else {
- msm_dp_hpd_unplug_handle(dp);
+ if (hpd_link_status == ISR_DISCONNECTED)
+ msm_dp_hpd_unplug_handle(dp);
}

pm_runtime_put_sync(&msm_dp_display->pdev->dev);
diff --git a/drivers/gpu/drm/msm/dp/dp_mst_drm.c b/drivers/gpu/drm/msm/dp/dp_mst_drm.c
index bb3898b1f6b1..71d3f63973e6 100644
--- a/drivers/gpu/drm/msm/dp/dp_mst_drm.c
+++ b/drivers/gpu/drm/msm/dp/dp_mst_drm.c
@@ -490,6 +490,40 @@ int msm_dp_mst_display_set_mgr_state(struct msm_dp *dp_display, bool state)
return rc;
}

+/* 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_data(mst->dp_aux, DP_SINK_COUNT_ESI, esi, 4);
+ if (rc < 0) {
+ 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_write_byte(mst->dp_aux, esi_res, ack[1]);
+ if (rc < 0) {
+ DRM_ERROR("DPCD esi_res failed. rc=%d\n", rc);
+ return;
+ }
+
+ 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 5d411529f681..08e145399cfc 100644
--- a/drivers/gpu/drm/msm/dp/dp_mst_drm.h
+++ b/drivers/gpu/drm/msm/dp/dp_mst_drm.h
@@ -9,5 +9,6 @@

int msm_dp_mst_init(struct msm_dp *dp_display, u32 max_streams, struct drm_dp_aux *drm_aux);
int msm_dp_mst_display_set_mgr_state(struct msm_dp *dp_display, bool state);
+void msm_dp_mst_display_hpd_irq(struct msm_dp *dp_display);

#endif /* _DP_MST_DRM_H_ */

--
2.43.0