Re: [PATCH v4 13/39] drm/msm/dp: introduce stream_id for each DP panel

[Dmitry Baryshkov]

On Fri, Apr 10, 2026 at 05:33:48PM +0800, Yongxing Mou wrote:
> From: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> 
> With MST, each DP controller can handle multiple streams.
> There shall be one dp_panel for each stream but the dp_display
> object shall be shared among them. To represent this abstraction,
> create a stream_id for each DP panel which shall be set by the
> MST stream. For SST, default this to stream 0.
> 
> Use the stream ID to control the pixel clock of that respective
> stream by extending the clock handles and state tracking of the
> DP pixel clock to an array of max supported streams. The maximum
> streams currently is 4.

Please mention that panels are going to be dynamically assigned to
actual stream IDs.

> 
> Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> Signed-off-by: Yongxing Mou <yongxing.mou@xxxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/dp/dp_ctrl.c    | 57 +++++++++++++++++++++++--------------
>  drivers/gpu/drm/msm/dp/dp_ctrl.h    |  2 +-
>  drivers/gpu/drm/msm/dp/dp_display.c | 24 ++++++++++++++--
>  drivers/gpu/drm/msm/dp/dp_display.h |  2 ++
>  drivers/gpu/drm/msm/dp/dp_panel.h   | 11 +++++++
>  5 files changed, 71 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index 120ec00884e5..fb6396727628 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -127,7 +127,7 @@ struct msm_dp_ctrl_private {
>  	unsigned int num_link_clks;
>  	struct clk_bulk_data *link_clks;
>  
> -	struct clk *pixel_clk;
> +	struct clk *pixel_clk[DP_STREAM_MAX];
>  
>  	union phy_configure_opts phy_opts;
>  
> @@ -139,7 +139,7 @@ struct msm_dp_ctrl_private {
>  
>  	bool core_clks_on;
>  	bool link_clks_on;
> -	bool stream_clks_on;
> +	bool stream_clks_on[DP_STREAM_MAX];
>  };
>  
>  static inline u32 msm_dp_read_ahb(const struct msm_dp_ctrl_private *ctrl, u32 offset)
> @@ -2176,39 +2176,40 @@ static bool msm_dp_ctrl_send_phy_test_pattern(struct msm_dp_ctrl_private *ctrl)
>  	return success;
>  }
>  
> -static int msm_dp_ctrl_on_pixel_clk(struct msm_dp_ctrl_private *ctrl, unsigned long pixel_rate)
> +static int msm_dp_ctrl_on_pixel_clk(struct msm_dp_ctrl_private *ctrl, unsigned long pixel_rate,
> +				    enum msm_dp_stream_id stream_id)
>  {
>  	int ret;
>  
> -	ret = clk_set_rate(ctrl->pixel_clk, pixel_rate * 1000);
> +	ret = clk_set_rate(ctrl->pixel_clk[stream_id], pixel_rate * 1000);
>  	if (ret) {
>  		DRM_ERROR("Failed to set pixel clock rate. ret=%d\n", ret);
>  		return ret;
>  	}
>  
> -	if (ctrl->stream_clks_on) {
> +	if (ctrl->stream_clks_on[stream_id]) {
>  		drm_dbg_dp(ctrl->drm_dev, "pixel clks already enabled\n");
>  	} else {
> -		ret = clk_prepare_enable(ctrl->pixel_clk);
> +		ret = clk_prepare_enable(ctrl->pixel_clk[stream_id]);
>  		if (ret) {
>  			DRM_ERROR("Failed to start pixel clocks. ret=%d\n", ret);
>  			return ret;
>  		}
> -		ctrl->stream_clks_on = true;
> +		ctrl->stream_clks_on[stream_id] = true;
>  	}
>  
>  	return ret;
>  }
>  
> -void msm_dp_ctrl_off_pixel_clk(struct msm_dp_ctrl *msm_dp_ctrl)
> +void msm_dp_ctrl_off_pixel_clk(struct msm_dp_ctrl *msm_dp_ctrl, enum msm_dp_stream_id stream_id)
>  {
>  	struct msm_dp_ctrl_private *ctrl;
>  
>  	ctrl = container_of(msm_dp_ctrl, struct msm_dp_ctrl_private, msm_dp_ctrl);
>  
> -	if (ctrl->stream_clks_on) {
> -		clk_disable_unprepare(ctrl->pixel_clk);
> -		ctrl->stream_clks_on = false;
> +	if (ctrl->stream_clks_on[stream_id]) {
> +		clk_disable_unprepare(ctrl->pixel_clk[stream_id]);
> +		ctrl->stream_clks_on[stream_id] = false;
>  	}
>  }
>  
> @@ -2228,7 +2229,7 @@ static int msm_dp_ctrl_process_phy_test_request(struct msm_dp_ctrl_private *ctrl
>  	 * running. Add the global reset just before disabling the
>  	 * link clocks and core clocks.
>  	 */
> -	msm_dp_ctrl_off_pixel_clk(&ctrl->msm_dp_ctrl);
> +	msm_dp_ctrl_off_pixel_clk(&ctrl->msm_dp_ctrl, ctrl->panel->stream_id);

Why are we using ctrl->panel again here for the stream-related
functions? Didn't you got rid of its usage few patches ago?

>  	msm_dp_ctrl_off_link(&ctrl->msm_dp_ctrl);
>  
>  	ret = msm_dp_ctrl_on_link(&ctrl->msm_dp_ctrl);
> @@ -2238,7 +2239,7 @@ static int msm_dp_ctrl_process_phy_test_request(struct msm_dp_ctrl_private *ctrl
>  	}
>  
>  	pixel_rate = ctrl->panel->msm_dp_mode.drm_mode.clock;
> -	ret = msm_dp_ctrl_on_pixel_clk(ctrl, pixel_rate);
> +	ret = msm_dp_ctrl_on_pixel_clk(ctrl, pixel_rate, ctrl->panel->stream_id);

And here...

>  
>  	msm_dp_ctrl_send_phy_test_pattern(ctrl);
>  
> @@ -1451,6 +1469,8 @@ void msm_dp_display_atomic_enable(struct msm_dp *msm_dp_display)
>  
>  	dp = container_of(msm_dp_display, struct msm_dp_display_private, msm_dp_display);
>  
> +	msm_dp_display_set_stream_info(msm_dp_display, dp->panel, 0);

DP_STREAM_0

> +
>  	rc = msm_dp_display_enable(dp);
>  	if (rc)
>  		DRM_ERROR("DP display enable failed, rc=%d\n", rc);

-- 
With best wishes
Dmitry