Re: [PATCH v4 27/39] drm/msm/dp: replace power_on with active_stream_cnt for dp_display

[Dmitry Baryshkov]

On Fri, Apr 10, 2026 at 05:34:02PM +0800, Yongxing Mou wrote:
> From: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> 
> For DP MST, the link clock and power domain resources stay on until
> both streams have been disabled OR we receive hotplug. Introduce an
> active_stream_cnt to track the number of active streams and necessary
> state handling. Replace the power_on variable with active_stream_cnt
> as power_on boolean works only for a single stream.
> 
> Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> Signed-off-by: Yongxing Mou <yongxing.mou@xxxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/dp/dp_audio.c   |  2 +-
>  drivers/gpu/drm/msm/dp/dp_display.c | 38 +++++++++++++++++++------------------
>  drivers/gpu/drm/msm/dp/dp_display.h |  2 +-
>  3 files changed, 22 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_audio.c b/drivers/gpu/drm/msm/dp/dp_audio.c
> index 41018e82efa1..035e230201fd 100644
> --- a/drivers/gpu/drm/msm/dp/dp_audio.c
> +++ b/drivers/gpu/drm/msm/dp/dp_audio.c
> @@ -284,7 +284,7 @@ int msm_dp_audio_prepare(struct drm_bridge *bridge,
>  	 * such cases check for connection status and bail out if not
>  	 * connected.
>  	 */
> -	if (!msm_dp_display->power_on) {
> +	if (!msm_dp_display->active_stream_cnt) {
>  		rc = -EINVAL;
>  		goto end;
>  	}
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 33d8539afee7..e6ecbb3a688e 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -657,15 +657,15 @@ int msm_dp_display_prepare(struct msm_dp *msm_dp_display)
>  	if (dp->link->sink_count == 0)
>  		return rc;
>  
> -	if (!msm_dp_display->power_on) {
> +	if (!msm_dp_display->active_stream_cnt) {

Okay, I'm now being lost between the names. When is prepare being
called? Is it still part of the atomic_enable()? Or atomic_pre_enable()?

>  		msm_dp_display_host_phy_init(dp);
>  		force_link_train = true;
> -	}
>  
> -	rc = msm_dp_ctrl_on_link(dp->ctrl, msm_dp_display->mst_active);
> -	if (rc)
> -		DRM_ERROR("Failed link training (rc=%d)\n", rc);
> -	// TODO: schedule drm_connector_set_link_status_property()
> +		rc = msm_dp_ctrl_on_link(dp->ctrl, msm_dp_display->mst_active);
> +		if (rc)
> +			DRM_ERROR("Failed link training (rc=%d)\n", rc);
> +		// TODO: schedule drm_connector_set_link_status_property()
> +	}

Again, this more than the scope of the commit message.

>  
>  	return msm_dp_ctrl_prepare_stream_on(dp->ctrl, force_link_train);
>  }
> @@ -674,18 +674,12 @@ static int msm_dp_display_enable(struct msm_dp_display_private *dp,
>  				 struct msm_dp_panel *msm_dp_panel)
>  {
>  	int rc = 0;
> -	struct msm_dp *msm_dp_display = &dp->msm_dp_display;
>  
>  	drm_dbg_dp(dp->drm_dev, "sink_count=%d\n", dp->link->sink_count);
> -	if (msm_dp_display->power_on) {
> -		drm_dbg_dp(dp->drm_dev, "Link already setup, return\n");
> -		return 0;
> -	}
>  
>  	rc = msm_dp_ctrl_on_stream(dp->ctrl, msm_dp_panel);
> -	if (!rc)
> -		msm_dp_display->power_on = true;
>  
> +	dp->msm_dp_display.active_stream_cnt++;
>  	return rc;
>  }
>  
> @@ -731,16 +725,14 @@ static void msm_dp_display_audio_notify_disable(struct msm_dp_display_private *d
>  static int msm_dp_display_disable(struct msm_dp_display_private *dp,
>  				  struct msm_dp_panel *msm_dp_panel)
>  {
> -	struct msm_dp *msm_dp_display = &dp->msm_dp_display;
> -
> -	if (!msm_dp_display->power_on)
> +	if (!dp->msm_dp_display.active_stream_cnt)
>  		return 0;
>  
>  	msm_dp_panel_disable_vsc_sdp(msm_dp_panel);
>  
>  	msm_dp_ctrl_off_pixel_clk(dp->ctrl, msm_dp_panel->stream_id);
>  
> -	msm_dp_display->power_on = false;
> +	dp->msm_dp_display.active_stream_cnt--;
>  
>  	drm_dbg_dp(dp->drm_dev, "sink count: %d\n", dp->link->sink_count);
>  	return 0;
> @@ -876,7 +868,7 @@ void msm_dp_snapshot(struct msm_disp_state *disp_state, struct msm_dp *dp)
>  	 * power_on status before dumping DP registers to avoid crash due
>  	 * to unclocked access
>  	 */
> -	if (!dp->power_on)
> +	if (!dp->active_stream_cnt)
>  		return;
>  
>  	msm_disp_snapshot_add_block(disp_state, msm_dp_display->ahb_len,
> @@ -1559,6 +1551,11 @@ void msm_dp_display_disable_helper(struct msm_dp *msm_dp_display,
>  
>  	dp = container_of(msm_dp_display, struct msm_dp_display_private, msm_dp_display);
>  
> +	if (!msm_dp_display->active_stream_cnt) {
> +		drm_dbg_dp(dp->drm_dev, "no active streams\n");
> +		return;
> +	}
> +
>  	msm_dp_ctrl_push_idle(dp->ctrl, msm_dp_panel);
>  	msm_dp_ctrl_mst_stream_channel_slot_setup(dp->ctrl);
>  	msm_dp_ctrl_mst_send_act(dp->ctrl);
> @@ -1579,6 +1576,11 @@ void msm_dp_display_unprepare(struct msm_dp *msm_dp_display)
>  
>  	dp = container_of(msm_dp_display, struct msm_dp_display_private, msm_dp_display);
>  
> +	if (msm_dp_display->active_stream_cnt) {
> +		drm_dbg_dp(dp->drm_dev, "stream still active, return\n");
> +		return;
> +	}
> +
>  	/* dongle is still connected but sinks are disconnected */
>  	if (dp->link->sink_count == 0)
>  		msm_dp_link_psm_config(dp->link, &dp->panel->link_info, true);
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h
> index 0ede5505be58..2548f67cd441 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.h
> +++ b/drivers/gpu/drm/msm/dp/dp_display.h
> @@ -18,7 +18,7 @@ struct msm_dp {
>  	struct drm_bridge *next_bridge;
>  	struct drm_bridge *bridge;
>  	bool audio_enabled;
> -	bool power_on;
> +	u32 active_stream_cnt;
>  	bool mst_active;
>  	unsigned int connector_type;
>  	bool is_edp;
> 
> -- 
> 2.43.0
> 

-- 
With best wishes
Dmitry