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

[Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>]

On Mon, Aug 25, 2025 at 10:16:17PM +0800, Yongxing Mou wrote:
> 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 | 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.

> +	}
>  
>  	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.

> +		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
> 

-- 
With best wishes
Dmitry