Re: [PATCH 4/5] drm/msm/dp: report IRQ_HPD as an IRQ-only notification

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

On Mon, Jun 29, 2026 at 10:48:06PM +0800, Yongxing Mou wrote:
> MST reuses the SST connector bridge to propagate HPD IRQ events through
> the bridge chain.
> 
> For IRQ_HPD notifications there is no connector state transition to
> report. Use connector_status_unknown together with
> DRM_CONNECTOR_DP_IRQ_HPD so that the bridge connector framework treats
> them as IRQ-only notifications and forwards them without modifying
> connector state.
> 
> The DP driver handles IRQ_HPD events based on
> DRM_CONNECTOR_DP_IRQ_HPD rather than connector status transitions.
> 
> Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
> ---
>  drivers/gpu/drm/msm/dp/dp_display.c   | 22 +++++++++-------------
>  drivers/soc/qcom/pmic_glink_altmode.c | 14 +++++++++-----

And which tree (and why) would be able to merge this patch?

>  2 files changed, 18 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index bc93b566fbca..4ee391cc7165 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -1119,14 +1119,10 @@ static irqreturn_t msm_dp_display_irq_thread(int irq, void *dev_id)
>  		drm_bridge_hpd_notify(dp->msm_dp_display.bridge,
>  				      connector_status_connected);
>  
> -	/* Send HPD as connected and distinguish it in the notifier */
> -	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);
> -	}
> +	if (hpd_isr_status & DP_DP_IRQ_HPD_INT_MASK)
> +		drm_bridge_hpd_notify_extra(dp->msm_dp_display.bridge,
> +					    connector_status_unknown,

It's _not_ unknown.

> +					    DRM_CONNECTOR_DP_IRQ_HPD);

This should be fixed in the MST patchset. You should not be doing any
actual handling in the ISR routing.

>  
>  	ret = IRQ_HANDLED;
>  
> @@ -1781,11 +1777,11 @@ void msm_dp_bridge_hpd_notify(struct drm_bridge *bridge,
>  	drm_dbg_dp(dp->drm_dev, "type=%d link hpd_link_status=0x%x, status=%d\n",
>  		   msm_dp_display->connector_type, hpd_link_status, status);
>  
> -	if (status == connector_status_connected) {
> -		if (hpd_link_status == ISR_IRQ_HPD_PULSE_COUNT ||
> -		    extra_status == DRM_CONNECTOR_DP_IRQ_HPD) {
> -			msm_dp_irq_hpd_handle(dp);
> -		} else if (hpd_link_status == ISR_HPD_REPLUG_COUNT) {
> +	if (extra_status == DRM_CONNECTOR_DP_IRQ_HPD ||
> +	    hpd_link_status == ISR_IRQ_HPD_PULSE_COUNT) {
> +		msm_dp_irq_hpd_handle(dp);

ANd here you missed the case when IRQ_HPD is being reported together
with the first HPD event.

> +	} else if (status == connector_status_connected) {
> +		if (hpd_link_status == ISR_HPD_REPLUG_COUNT) {
>  			msm_dp_hpd_unplug_handle(dp);
>  			msm_dp_hpd_plug_handle(dp);
>  		} else {
> diff --git a/drivers/soc/qcom/pmic_glink_altmode.c b/drivers/soc/qcom/pmic_glink_altmode.c
> index 946eb20b8f83..28ab8cbb5ef9 100644
> --- a/drivers/soc/qcom/pmic_glink_altmode.c
> +++ b/drivers/soc/qcom/pmic_glink_altmode.c
> @@ -373,11 +373,15 @@ static void pmic_glink_altmode_worker(struct work_struct *work)
>  		else
>  			conn_status = connector_status_disconnected;
>  
> -		drm_aux_hpd_bridge_notify_extra(&alt_port->bridge->dev,
> -						conn_status,
> -						alt_port->hpd_irq ?
> -						DRM_CONNECTOR_DP_IRQ_HPD :
> -						DRM_CONNECTOR_NO_EXTRA_STATUS);
> +		if (alt_port->hpd_irq) {
> +			drm_aux_hpd_bridge_notify_extra(&alt_port->bridge->dev,
> +							connector_status_unknown,

And this is completely wrong. The AltMode driver (btw, you also missed
the normal altmode driver for DP) doesn't know if it should handle the
events in some way. It should report the HPD and IRQ_HPD as is.

> +							DRM_CONNECTOR_DP_IRQ_HPD);
> +		} else {
> +			drm_aux_hpd_bridge_notify_extra(&alt_port->bridge->dev,
> +							conn_status,
> +							DRM_CONNECTOR_NO_EXTRA_STATUS);
> +		}
>  	} else if (alt_port->mux_ctrl == MUX_CTRL_STATE_TUNNELING) {
>  		if (alt_port->svid == USB_TYPEC_TBT_SID)
>  			pmic_glink_altmode_enable_tbt(altmode, alt_port);
> 
> -- 
> 2.43.0
> 

-- 
With best wishes
Dmitry

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