Re: [PATCH v3 31/38] drm/msm/dp: add HPD callback for dp MST
From: Yongxing Mou
Date: Tue Mar 24 2026 - 09:18:33 EST
On 8/27/2025 2:40 AM, Dmitry Baryshkov wrote:
On Mon, Aug 25, 2025 at 10:16:17PM +0800, Yongxing Mou wrote:Emm ... maybe here we can directly call msm_dp_mst_display_hpd_irq..
From: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
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@xxxxxxxxxxx>
Signed-off-by: Yongxing Mou <yongxing.mou@xxxxxxxxxxxxxxxx>
---
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);
Why is it a part of this patch?? It has nothing to do with MST.
I tried an alternative approach by calling the MST IRQ handler from msm_dp_bridge_hpd_notify(). I expected that when hpd_isr_status == DP_DP_IRQ_HPD_INT_MASK, the hpd_link_status read in msm_dp_bridge_hpd_notify() would be ISR_IRQ_HPD_PULSE_COUNT. That way, we could handle both SST and MST interrupt paths in msm_dp_irq_hpd_handle(). However, hpd_link_status only reports ISR_CONNECTED. So I had to move the MST IRQ handling into the IRQ thread. Do you have any suggestions on this?
Will fix it.+ }
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);
It's DPCD, not dpcd.
Got it.+ 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)
No empty space, drm_dp_dpcd_write_byte().
+ 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